The Mexican-American War is fought over the U.S. annexation of Texas against Mexico’s agreement. The war leads to many historical losses for Mexican and Indigenous communities: the loss of land, original identities, language, cultural knowledge, and family relationships. It brings about forced assimilation and marginalization. Indigenous and Mexican people living in the present-day U.S. Southwest are allowed to either keep their land and become U.S. citizens or to relocate across the new Mexican border. Many people decide to stay. The U.S. promises to protect land, language, and cultural rights, but largely fails to honor that treaty.