Working in the Tolima region inhabited by Amerindians and the renowned indigenous leader Quintin Lame, they also published a study indicating the indigenous culture of the local populations and also indicated the blood type variations among the indigenous groups of the Pijao in the Department of Tolima as further proof of their Amerindian identity as these tribes were arguing over rights to their ancestral territories.
Marshall & Seijas (1973) did not detect significative connections between Pijao and other unclassified languages of the area: Colima, Muzo, Pantágora, and Panche, but these are even more poorly attested than Pijao.