Several social, political, and economic transitions marked the conquest and cultural exchange of California's early history. Native American communities were transformed as a result of European exploration and settlement in the late 18th century. Spain constructed missions and military presidios in Alta California to increase Spanish settlement in the new colony and encourage religious conversion among Native Americans. The mission structures remained long after the collapse of Spanish authority. Following Mexico's independence from Spain in 1821, vast land grants helped elite Californio society flourish until the 1880s. Today, the state's wealth continues to be defined through the utilization of its rich resources and its immense natural and human potential.