sentences:  In December 1821, the first U.S. colonists crossed into the granted territory by land and sea, on the Brazos River in present-day Brazoria County, Texas.Austin's plan for an American colony was thrown into turmoil by Mexico's gaining independence from Spain in 1821.Governor Martínez informed Austin that the "junta instituyente", the new rump congress of the government of Agustín de Iturbide of Mexico, refused to recognize the land grant authorized by Spain.