The Republic of Texas (Spanish: República de Tejas), or simply Texas, was a sovereign country in North America[4] from March 2, 1836, to February 19, 1846. Texas was bordered by Mexico to the west and southwest, the Gulf of Mexico to the southeast, the two U.S. states of Louisiana and Arkansas to the east and northeast, and U.S. unorganized territory encompassing parts of the current U.S. states of Oklahoma, Kansas, Colorado, and Wyoming to the north. The Texas Revolution began when hostilities broke out on October 2, 1835, shortly before the regime of Mexican President and General Antonio López de Santa Anna adopted a new Mexican constitution known as the Siete Leyes that abolished the authority of the states under the federal republic and established a centralized government. The revolution lasted for over six months. On March 2, 1836, delegates in convention proclaimed the Texas Declaration of Independence. Major fighting ended on April 21, 1836, with the Treaties of Velasco that ended the fighting and secured Texas' independence.