Ceramic finds suggest that the site was first occupied at the beginning of the Late Preclassic period, possibly with the E-Group astronomical complex in the site core being built at around that time. From that time onwards Ixtonton was the most important city in the Dolores Valley and a large portion of the Maya Mountains, and it had no serious challenger throughout the Early Classic period. The site was heavily occupied in the Late Classic and large quantities of finds have been recovered that date to the Terminal Classic, with evidence that occupation continued into the Postclassic. During the Late Classic, Ixkun and Ixtutz both developed sufficiently to rival Ixtonton, but this did not last and Ixtonton continued as the most prominent site in the region.