In 1826, the Kingdom of Ligor broke its promise and attempted to conquer Perak. A small British expeditionary force thwarted the attack. The Sultan of Perak then ceded to the British the area of Dindings and Pangkor (the two now constitute Manjung District) so that the British could suppress pirate activity along the Perak coast where it became part of the Straits Settlements. The same year, the British and Siam concluded a new treaty. Under the Burney Treaty, signed by British Captain Henry Burney and the Siamese government, the British undertook not to intercede in the affairs of Kedah despite their friendly relations with Kedah's ruler, and the Siamese undertook not to attack either Perak or Selangor.