<P> The Mexican government's policy of settlement of US citizens in its province of Tejas was aimed at expanding control into Comanche lands, the Comancheria . Instead of settlement occurring in the central and west of the province, people settled in East Texas, where there was rich farmland and which was contiguous to southern US slave states . As settlers poured in from the US, the Mexican government took steps to discourage further settlement, including its 1829 abolition of slavery . </P> <P> In 1836, Mexico was relatively united in refusing to recognize the independence of Texas . Mexico threatened war with the United States if it annexed the Republic of Texas . Meanwhile, U.S. President Polk's assertion of Manifest Destiny was focusing United States interest on westward expansion beyond its existing national borders . </P> <P> During the Spanish colonial era, the Californias (i.e., the Baja California peninsula and Alta California) were sparsely settled . After Mexico became independent, it shut down the missions and reduced its military presence . </P> <P> In 1842, the US minister in Mexico, Waddy Thompson Jr., suggested Mexico might be willing to cede Alta California to settle debts, saying: "As to Texas, I regard it as of very little value compared with California, the richest, the most beautiful, and the healthiest country in the world...with the acquisition of Upper California we should have the same ascendency on the Pacific...France and England both have had their eyes upon it ." </P>

How did the us get land from mexico