Caddo Native Americans inhabited the Dallas area before it was claimed, along with the rest of Texas, as a part of the Spanish Viceroyalty of New Spain in the 1500s. The area was also claimed by the French, but in 1819 the Adams-Onís Treaty officially placed Dallas well within Spanish territory by making the Red River the northern boundary of New Spain.
Another European who probably visited the Dallas area was Athanase de Mezieres in 1778. De Mezieres, a Frenchman then in the service of the King of Spain, probably crossed the West Fork of the Trinity River near present-day Fort Worth, having followed the western edge of the Eastern Cross Timbers from the Tawakoni Village on the Brazos River near present Waco. He then proceeded north to the Red River. He wrote:
“ It is worthy to note that from the Brazos River on which the Tuacanas are established, and until one reaches the river which bathes the village of the Taovayzes (Red River), one sees on the right a forest that the natives appropriately call the Grand Forest. ...it is very dense, but not very wide. It seems to be there as a guide to even the most inexperienced, and to give refuge in this dangerous region to those who, few in number and lacking in courage, wish to go from one village to another. -De Mezieres”
(Right) Map of Downtown Dallas (1871) shows the Trinity River running through the edge of the city. Where present day Dealy Plaza is located. De Mezieres' biographer, Bolton, was convinced de Mezieres was describing the Eastern Cross Timbers and the route would have him crossing the West Fork of the Trinity River between the present Fort Worth and Arlington.
Present-day Dallas remained under Spanish rule until 1821, when Mexico declared independence from Spain, and the area became part of the Mexican state of Coahuila y Tejas. The Republic of Texas broke off from Mexico in 1836 and remained an independent country for nearly 10 years.