The Kalagan are the Ismalized indigenous people in the Western Davao gulf area. The Kalagan became Muslim probably during the middle of the 19th century, due to a combination of the following factors:
1. The political pressure and/or influence of the Tausug migrants in Davao.
2. Extensive exposure and/or contact with the communities of their Maguindanaon neighbors.
3. Inter-marriages of Kalagan and Maguindanaon and/or Tausug.
The Kalagan are mostly found in Davao city, district of Sirawan, around Tagum, Davao del Norte, Mati-in Davao Oriental, some places in Davao del Sur and the other two Davao provinces. The Kalagan use Tagakaolo language, but some Tausug and Maguindanaon words are increasingly used by them.
They are agriculturists, cultivating rice, corn, abaca and coconut for cash crops, while those living along the coast engage in fishing.