Final answer:
The people living in the areas taken over by the United States during this period experienced displacement, relocation, or forced migration. The United States government questioned the validity of land deeds and took the lands of tejanos, californios, and others.
Step-by-step explanation:
The people who lived in the areas taken over by the United States during this period, including Native people and Mexican citizens, experienced displacement, relocation, or forced migration. The United States government questioned the validity of Mexican and Spanish land deeds and ultimately took the lands of tejanos, californios, and others. Mexicans and Mexican-Americans lost their lands in Texas, California, and New Mexico, leading to the loss of property and cultural disruption for these communities.