opinion: Justice Powell
  delivered the opinion of the Court.
  This case presents the question whether the State of Montana may tax the Blackfeet Tribe’s royalty interests under oil and gas leases issued to non-Indian lessees pursuant to the Indian Mineral Leasing Act of 1938, ch. 198, 52 Stat. 347, 25 U. S. C. § 396a et seq. (1938 Act).
  I
  Appellants Blackfeet Tribe filed this suit m the United States District Court for the District of Montana challenging the application of several Montana taxes to the Tribe’s royalty interests in oil and gas produced under leases issued by the Tribe. The leases involved unallotted lands on the Tribe’s reservation and were granted to non-Indian lessees in accordance with the 1938 Act. The taxes at issue were paid to the State by the lessees and then deducted by the lessees from the royalty payments made to the Tribe. The Blackfeet sought declaratory and injunctive relief against enforcement of the state tax statutes. The Tribe argued, to the District Court that the 1938 Act did not authorize the State to tax tribal royalty interests and thus that the taxes were unlawful. The District Court rejected this claim and granted the State’s motion for summary judgment. The court held that the state taxes were authorized by a 1924 statute, Act of May 29, 1924, ch. 210, 43 Stat. 244, 25 U. S. C. § 398 (1924 Act), and that the 1938 Act, under which the leases in question were issued, did not repeal this authorization. The District Court was not persuaded by a 1977 opinion of the Department of the Interior supporting the Blackfeet’s position, noting that the Department previously had expressed contrary views, 507 F. Supp. 446, 451 (1981).
  A panel of the United States Court of Appeals for the Ninth Circuit affirmed the District Court’s decision. On rehearing en banc, the Court of Appeals reversed in part and remanded the case for further proceedings. 729 F. 2d 1192 (1984). The court held that the tax authorization in the 1924 Act was not repealed by the 1938 Act and thus remained in effect for leases executed pursuant to the 1924 Act. The court also held, however, that the 1938 Act did not incorporate the tax provision of the 1924 Act, and therefore that its authorization did not apply to leases executed after the enactment of the 1938 Act. The court reasoned that the taxing provision of the 1924 Act was inconsistent with the policies of the Indian Reorganization Act of 1934, 48 Stat. 984, 25 U. S. C. §461 et seq. (IRA). Since the 1938 Act was adopted specifically to harmonize Indian leasing laws with the IRA, Congress could not have intended the 1924 Act to apply to leases issued under the 1938 Act. The court remanded the case to the District Court to determine where the legal incidence of the taxes fell, and directed the court to consider whether, if the taxes fell on the oil and gas producers instead of the Indians, the taxes were pre-empted by federal law. We granted the State’s petition for certiorari to resolve whether Montana may tax Indian royalty interests arising out of leases executed after the adoption of the 1938 Act. 469 U. S. 815 (1984). We affirm the decision of the en banc Court of Appeals that it may not.
  II
  Congress first authorized mineral leasing of Indian lands in the Act of Feb. 28, 1891, 26 Stat. 795, 25 U. S. C. §397 (1891 Act). The Act authorized leases for terms not to exceed 10 years on lands “bought and paid for” by the Indians. The 1891 Act was amended by the 1924 Act. The amendment provided in pertinent part:
  “Unallotted land . . . subject to lease for mining purposes for a period of ten years under section 397. . . may be leased ... by the Secretary of the Interior, with the consent of the [Indian] council... , for oil and gas mining purposes for a period of not to exceed ten years, and as much longer as oil or gas shall be found in paying quantities, and the terms of any existing oil and gas mining lease may in like manner be amended by extending the term thereof for as long as oil or gas shall be found in paying quantities: Provided, That the production of oil and gas and other minerals on such lands may be taxed by the State in which said lands are located in all respects the same as production on unrestricted lands, and the Secretary of the Interior is authorized and directed to cause to be paid the tax so assessed against the royalty interests on said lands: Provided, however, That such tax shall not become a lien or charge of any kind or character against the land or the property of the Indian owner.” Act of May 29, 1924, ch. 210, 43 Stat. 244, 25 U. S. C. §398.
  Montana relies on the first proviso in the 1924 Act in claiming the authority to tax the Blackfeet’s royalty payments.
  In 1938, Congress adopted comprehensive legislation in an effort to “obtain uniformity so far as practicable of the law relating to the leasing of tribal lands for mining purposes.” S. Rep. No. 985, 75th Cong., 1st Sess., 2 (1937) (hereafter Senate Report). Like the 1924 Act, the 1938 Act permitted, subject to the approval of the Secretary of the Interior, mineral leasing of unallotted lands for a period not to exceed 10 years and as long thereafter as minerals in paying quantities were produced. The Act also detailed uniform leasing procedures designed to protect the Indians. See 25 U. S. C. §§396b-396g. The 1938 Act did not contain a provision authorizing state taxation; nor did it repeal specifically the authorization in the 1924 Act. A general repealer clause was provided in §7 of the Act: “All Act [sic] or parts of Acts inconsistent herewith are hereby repealed.” The question presented by this case is whether the 1924 Act’s proviso that authorizes state taxation was repealed by the 1938 Act, or if left intact, applies to leases executed under the 1938 Act.
  I — ( HH J — I
  The Constitution vests the Federal Government with exclusive authority over relations with Indian tribes. Art. I, § 8, cl. 3; see Oneida Indian Nation v. County of Oneida, 414 U. S. 661, 670 (1974), citing Worcester v. Georgia, 6 Pet. 515, 561 (1832). As a corollary of this authority, and in recognition of the sovereignty retained by Indian tribes even after formation of the United States, Indian tribes and individuals generally are exempt from state taxation within their own territory. In The Kansas Indians, 5 Wall. 737 (1867), for example, the Court ruled that lands held -by Indians in common as well as those held in severalty were exempt from state taxation. It explained that “[i]f the tribal organization . . . is preserved intact, and recognized by the political department of the government as existing, then they are a ‘people distinct from others,’. . . separated from the jurisdiction of [the State], and to be governed exclusively by the government of the Union.” Id., at 755. Likewise, in The New York Indians, 5 Wall. 761 (1867), the Court characterized the State’s attempt to tax Indian reservation land as extraordinary, an “illegal” exercise of state power, id., at 770, and “an unwarrantable interference, inconsistent with the original title of the Indians, and offensive to their tribal relations,” id., at 771. As the Government points out, this Court has never wavered from the views expressed in these cases. See, e. g., Bryan v. Itasca County, 426 U. S. 373, 375-378, 392-393 (1976); Moe v. Salish & Kootenai Tribes, 425 U. S. 463, 475-476 (1976); Mescalero Apache Tribe v. Jones, 411 U. S. 145, 148 (1973).
  In keeping with its plenary authority over Indian affairs, Congress can authorize the imposition of state taxes on Indian tribes and individual Indians. It has not done so often, and the Court consistently has held that it will find the Indians’ exemption from state taxes lifted only when Congress has made its intention to do so unmistakably clear. E. g., Bryan v. Itasca County, supra, at 392-393; Carpenter v. Shaw, 280 U. S. 363, 366-367 (1930). The 1924 Act contains such an explicit authorization. As a result, in British-American Oil Producing Co. v. Board of Equalization of Montana, 299 U. S. 159 (1936), the Court held that the State of Montana could tax oil and gas produced under leases executed under the 1924 Act.
  The State urges us that the taxing authorization provided in the 1924 Act applies to leases executed under the 1938 Act as well. It argues that nothing in the 1938 Act is inconsistent with the 1924 taxing provision and thus that the provision was not repealed by the 1938 Act. It cites decisions of this Court that a clause repealing only inconsistent Acts “implies very strongly that there may be acts on the same subject which are not thereby repealed,” Hess v. Reynolds, 113 U. S. 73, 79 (1885), and that such a clause indicates Congress’ intent “to leave in force some portions of former acts relative to the same subject-matter,” Henderson’s Tobacco, 11 Wall. 652, 656 (1871). The State also notes that there is a strong presumption against repeals by implication, e. g., United States v. Borden Co., 308 U. S. 188, 198 (1939), especially an implied repeal of a specific statute by a general one, Morton v. Mancari, 417 U. S. 535, 550-551 (1974). Thus, in the State’s view, sound principles of statutory construction lead to the conclusion that its taxing authority under the 1924 Act remains intact.
  The State fails to appreciate, however, that the standard principles of statutory construction do not have their usual force in cases involving Indian law. As we said earlier this Term, “[t]he canons of construction applicable in Indian law are rooted in the unique trust relationship between the United States and the Indians.” Oneida County v. Oneida Indian Nation, 470 U. S. 226, 247 (1985). Two such canons are directly applicable in this case: first, the States may tax Indians only when Congress has manifested clearly its consent to such taxation, e. g., Bryan v. Itasca County, supra, at 393; second, statutes are to be construed liberally in favor of the Indians, with ambiguous provisions interpreted to their benefit, e. g., McClanahan v. Arizona State Tax Comm’n, 411 U. S. 164, 174 (1973); Choate v. Trapp, 224 U. S. 665, 675 (1912). When the 1924 and 1938 Acts are considered in light of these principles, it is clear that the 1924 Act does not authorize Montana to enforce its tax statutes with respect to leases issued under the 1938 Act.
  I — I <1
  Nothing in either the text or legislative history of the 1938 Act suggests that Congress intended to permit States to tax tribal royalty income generated by leases issued pursuant to that Act. The statute contains no explicit consent to state taxation. Nor is there any indication that Congress intended to incorporate implicitly in the 1938 Act the taxing authority of the 1924 Act. Contrary to the State’s suggestion, under the applicable principles of statutory construction, the general repealer clause of the 1938 Act cannot be taken to incorporate consistent provisions of earlier laws. The clause surely does not satisfy the requirement that Congress clearly consent to state taxation. Nor would the State’s interpretation satisfy the rule requiring that statutes be construed liberally in favor of the Indians.
  Moreover, the language of the taxing provision of the 1924 Act belies any suggestion that it carries over to the 1938 Act. The tax proviso in the 1924 Act states that “the production of oil and gas and other minerals on such lands may be taxed by the State in which said lands are located . . . .” 25 U. S. C. §398. Even applying ordinary principles of statutory construction, “such lands” refers to “[ujnallotted land . . . subject to lease for mining purposes . . . under section 397 [the 1891 Act].” When the statute is “liberally construed ... in favor of the Indians,” Alaska Pacific Fisheries v. United States, 248 U. S. 78, 89 (1918), it is clear that if the tax proviso survives at all, it reaches only those leases executed under the 1891 Act and its 1924 amendment.
  V
  In the absence of clear congressional consent to taxation, we hold that the State may not tax Indian royalty income from leases issued pursuant to the 1938 Act. Accordingly, the judgment of the Court of Appeals is
  Affirmed.
  At issue are the taxes adopted in the following statutes: the Oil and Gas Severance Tax, Mont. Code Ann. § 15-36-101 et seq. (1983); Oil and Gas Net Proceeds, Mont. Code Ann. § 15-23-601 et seq. (1983); Oil and Gas Conservation, Mont. Code Ann. §82-11-101 et seq. (1983); and the Resource Indemnity Trust Tax, Mont. Code Ann. § 15-38-101 et seq. (1983).
  The Blackfeet properly invoked the jurisdiction of the District Court pursuant to 28 U. S. C. § 1362, which provides:
  “The district courts shall have original jurisdiction of all civil actions, brought by any Indian tribe or band with a governing body duly recognized by the Secretary of the Interior, wherein the matter in controversy arises under the Constitution, laws, or treaties of the United States.”
  As we ruled in Moe v. Salish & Kootenai Tribes, 425 U. S. 463 (1976), a suit by an Indian tribe to enjoin the enforcement of state tax laws is cognizable in the district court under § 1362 despite the general ban in 28 U. S. C. § 1341 against seeking federal injunctions of such laws. See id., at 474-475.
  In British-American Oil Producing Co. v. Board of Equalization of Montana, the Court interpreted the statutory leasing authority over lands “bought and paid for by the Indians” to include land reserved for the Indians in exchange for their cession or surrender of other lands or rights, as well as that acquired by Indians for money.
  Indeed, the Court has held that although tax exemptions generally are to be construed narrowly, in “the Government’s dealings with the Indians the rule is exactly the contrary. The construction, instead of being strict, is liberal. . . .” Choate v. Trapp, 224 U. S., at 675.
  In fact, the legislative history suggests that Congress intended to replace the 1924 Act’s leasing scheme with that of the 1938 Act. As the Court of Appeals recognized, Congress had three major goals in adopting the 1938 Act: (i) to achieve “uniformity so far as practicable of the law relating to the leasing of tribal lands for mining purposes,” Senate Report 2; H. R. Rep. No. 1872, 75th Cong., 3d Sess., 1 (1938); (ii) to “bring all mineral-leasing matters in harmony with the Indian Reorganization Act,” Senate Report 3; H. R. Rep. No. 1872, supra, at 3; and (iii) to ensure that Indians receive “the greatest return from their property,” Senate Report 2; H. R. Rep. No. 1872, supra, at 2. As the Court of Appeals suggested, these purposes would be undermined if the 1938 Act were interpreted to incorporate the taxation proviso of the 1924 Act. See 729 F. 2d 1192, 1196-1198 (CA9 1984).
  The Court of Appeals held that the 1938 Act did not repeal implicitly the 1924 consent to state taxation and thus that this consent continues in force with respect to leases issued under the 1924 or 1891 Acts. Id., at 1200. Because the Blackfeet have not sought review on this question, we need not decide whether the Court of Appeals was correct. We assume for purposes of this case that the 1924 Act’s authorization remains in effect for leases executed pursuant to that statute.
  We are likewise unpersuaded by the State’s contention that we should defer to the administrative interpretation that the 1924 taxing proviso applies to leases executed under the 1988 Act. The State relies on opinions of the Department of the Interior in making this argument. As the Court of Appeals pointed out, however, the administrative record is not as strongly consistent as the State contends. Id., at 1202-1203. The opinions issued prior to 1956 did not mention the 1938 Act or leases executed pursuant thereto. Thus, at best, they did not address the issue presented by this case, but simply assumed that the 1924 Act and this Court’s decision in British-American Oil Producing Co. v. Board of Equalization of Montana, 299 U. S. 159 (1936), applied to leases executed under the 1938 Act. It was not until its 1956 opinion that the Department of the Interior considered the relationship between the 1938 and 1924 Acts. The Department then held that the taxing provision had not been repealed by the 1938 Act. This 1956 opinion was unpublished and did not analyze whether Congress had intended the 1924 Act’s provision to apply to leases entered pursuant to the 1938 Act. A 1966 opinion relied on the 1956 opinion. In 1977, the Department reconsidered the issue carefully and in far greater detail than it had in 1956, and reversed its prior decision. See 729 F. 2d, at 1202-1203. On this record, we cannot accept the premise of the State’s argument for deference to agency interpretation, that is, that the Department had a consistent 40-year practice. This is particularly true where, as here, the language and purpose of the 1938 Act are — for the reasons set forth above — clearly to the contrary.
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