Mexican-American war
Yes, but Mexico refused to negotiate.
You mean before the Mexican-American War? That was the Nueces Strip.
The Mexican Cession was the name granted the region of the modern day Southwestern US that Mexico gave up to the US. Before this, it was considered another part of Mexico.
Both share a common border, both are in the Southwestern United States; both border the country of Mexico and both used to belong to Mexico before the Mexican-American War (1846-1848).
Mexico was known as New Spain before it gained independence from Spain in 1821.
Agustin I of the Mexican Empire. However, his reign was short-lived, before some Mexican generals staged a coup d'etat and switched Mexico into a Republic.
Mexican-American war
Both Native American peoples found in the Americans at the time of Mexico's conquest, as well as Spanish conquistadors who conquered and settled Mexico from 1521 until 1821, when Mexico won its independence war against Spain.
Yes, but Mexico refused to negotiate.
Before the Mexican Revolution that gained independence of Mexico from Spain, Spain laid claim to the area along the North American Pacific coast that includes what is now the state of California.
Before the Mexican/American War, Mexico claimed it was the Nueces river, while Texans claimed it was the Rio Grande.
You mean before the Mexican-American War? That was the Nueces Strip.
Mexico; as Texas had been a state of Mexico before it declared independence in 1836 because of this it's annexation into the US in 1848 meant that Mexico wouldn't be able to recover Texas. The issue of Texas also caused the American-Mexican War 1846-48 in which Mexico lost California, Nevada, Arizona and New Mexico to the US.
Approximately 21% of Mexico's population identifies as indigenous.
No. Black people were in such position before Mexico attained its independence, mainly due to being slaves. However, Mexican independence ideals also advocated abolitionism and even if they were one of the most economically "challenged" classes, they were quickly absorbed into the general population.
California was originally part of Mexico before the Mexican-American War (1846-1848) but before that, there were very few people on such lands (less than 4,000). They were Mexican after all, but had very little connections to Mexico, as the capital was too far away and almost no news reached these lands.