Major construction at Tikal was already taking place in the Late Preclassic period , first appearing around 400 – 300 BC , including the building of major pyramids and platforms , although the city was still dwarfed by sites further north such as El Mirador and Nakbe . At this time , Tikal participated in the widespread Chikanel culture that dominated the Central and Northern Maya areas at this time – a region that included the entire Yucatan Peninsula including northern and eastern Guatemala and all of Belize .