Terrence Kaufman suggested that the lowlands were populated by proto - Mayan speaking people from the highlands .
Proto - Mayan languages split around 2200 BCE in the highlands and splinter groups appear in the lowlands around 1400 BCE .
Terrence Kaufman suggested that the lowlands were populated by proto - Mayan speaking people from the highlands because Proto - Mayan languages split around 2200 BCE in the highlands and splinter groups appear in the lowlands around 1400 BCE .