It appears that the Bila-an once inhabited the district about Lake Buluan, but the pressure of the Moro has forced most of them from that region toward the mountains to the south and east.  They have taken possession of both sides of this mountain range, except for the lower eastern slopes where they have encountered the Tagakaolo.

The other tribes probably landed on the southern or southeastern coast of the Island, from whence they have gradually moved to their present habitats.

Intermarriage between the tribes, Moro raids, warfare with the accompanying capture of slaves, and the possible influence of boat-loads of castaways, all have to be considered in dealing with the types found in Davao District.  We have already seen that the physical measurements indicate a complex racial history.

After giving full credit to all these influences, however, it does not appear to the writer that such radical differences exist between the tribes as will justify us in assigning to them different ancestry or places of origin.  The summarized description of the Bagobo given on page 56 would, with only, slight modification, apply to all the other tribes, with the exception of certain groups of the Ata in which the Negrito element is very pronounced.  In brief, the various influences that have been at work on one group have influenced all the others, since their arrival on the island of Mindanao.

This conclusion is further justified by the language in which a large per cent of the words in daily use are common to all the groups.  Even the Bila-an dialect, which differs more from all the others than do any of those from one another, has so many words in common with the coast tongues and is so similar in structure that one of my native boys, who never before had seen a Bila-an, was able freely to carry on a conversation within a few days after his arrival in one of their most isolated settlements.

Similar as are the people and their dialects, the cultural agreements are even more noticeable.  Taking the Bagobo as a starting point, we find a highly developed culture which, with a few minor changes, holds good for the tribes immediately surrounding.  These in turn differ little from their neighbors, although from time to time some new forms appear.  The Cibolan type of dwelling, with its raised platform at one end and box-like enclosures along the side walls, is met with until the Mandaya territory is approached, while, with little variation, the house furnishings and utensils in daily use are the same throughout the District.  The same complicated method of overtying, dyeing, and weaving of hemp employed in the manufacture of women’s skirts is in use from Cateel in the north to Sarangani Bay in the south, while in the manufacture of weapons the iron worker in Cibolan differs not at all from his fellow-craftsman among the Mandaya.  Here we are confronted by the objection that, so far as is known, no iron work