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