Answer:
The Republic of Texas
Explanation:
Since its independence from Spain in 1821, Mexico encouraged Americans to settle in the territory of Texas, but by the late 1820s, the Americans surpassed the Mexican population and there was a growing concern. Mexico tried to enforce the use of Spanish and the Catholic religion.
Conflict ensued and in 1835 it turned into a full violent confrontation.
In 1836 Texas declared its independence from Mexico and soon after drafted the constitution. Texas remained an independent Republic until 1845.