Alonso Alvarez de Pineda was the Spanish explorer who first mapped the coastline of Texas. Alvarez de Pineda left Jamaica in early 1519 and sailed west to follow the northern coastline of the Gulf. He sailed west from the Florida Keys to hug the Gulf Coast. The expedition established the remainder of the boundaries of the Gulf of Mexico, while disproving the idea of sea passage to Asia and verifying that Florida was a peninsula instead of an island. His map is the first known document of Texas history and was the first map of the Gulf Coast region of the United States.