The bankrupt federal government was unable to provide much military assistance to the settlers in Texas, who faced frequent raids by native tribes. Hoping that an influx of settlers could control the raids, in 1824 the government appointed "empresarios" to encourage families from the United States and Europe to settle in Texas. However, as the number of settlers from the US and other non-Spanish-speaking areas increased in Texas, Mexican authorities became apprehensive that the United States might wish to annex the area, possibly using force. On April 6, 1830, the Mexican government passed a series of laws restricting immigration from the United States into Texas. The laws also canceled all unfilled "empresario" contracts and called for the first enforcement of customs duties.