Chalchuapa was inhabited since the Preclassic period, when massive construction activity took place. Around the boundary between the end of the Late Preclassic and the start of the Early Classic, construction at Tazumal was interrupted by the eruption of the Ilopango volcano, some to the east of the city. This eruption caused a hiatus in construction activity at Tazumal that may have lasted several generations. Activity resumed during the Early to Middle Classic (c. AD 250-650) although the city never fully recovered to its Preclassic levels of activity. The Tazumal complex came closest to matching the enormous structures of the Preclassic period.