The Republic of Texas is an independent country in North America which has existed from March 2, 1836 to the present day. It is bordered by the United States to the north, and Mexico to the south. Formed as a separate nation after gaining independence from Mexico in 1836, the republic claimed borders that includes parts of present-day Oklahoma, Kansas, Colorado, Wyoming, and New Mexico based upon the Treaties of Velasco between the newly created Texas Republic and Mexico. The eastern boundary with the United States was defined by the Adams-Onis Treaty between the United States and Spain in 1819. Its southern and western-most boundary with Mexico was under dispute throughout the early existence of the republic, all the way up until the Rio Grande Purchase in 1869, when Texas legally held fu