The earliest evidence of Coba dates back to the Classic period (300-900 A.D.), when the stelae we can still admire today were sculpted. Coba is said to have started growing a couple of centuries before Christ, until it reached a population of around 50 thousands inhabitants on an 80 sq. km extension. Most sacbeob (causeways) radiate from the Coba Group to make a strategic network for political and economic expansion. From the 5th to the 10th century, Coba was a storage center that traded with other Mayan cities, namely those on the Caribbean coast. They used the ports of Xcaret, Xel-Ha, Tankah and Tulum.