 For about twenty years in the late 18th century, San Blas was one of the busiest ports and shipbuilding centers on the Pacific coast of the Americas, rivaling Acapulco, the eastern terminus of the trans-Pacific Manila galleon convoy.At its height, the town had 30,000 inhabitants and became headquarters of Spain's General of the Southern Seas.During the 1900s, San Blas served as the arrival port for thousands of Yaqui men, women and children forcibly removed from their lands and sold into slavery.