To talk about the origins of Betawi would be like illustrating a complicated history of Jakarta, then known as Batavia. Biologically, those who identify themselves as ‘Betawi’ are the descendants from a mixed ethnicity and nation during the colonialism era in Batavia. Hence, the Betawi tribe in itself is considered to be a novel ethnicity that had only begun to form from the 17th - 18th century. This ethnic group was formed by other ethnicity that has prior existed in Batavia, such as the Sundanese, Javanese, Arabians, Balinese, Chinese and so much others. Of course, the case to the exact timing in which the Betawi tribe existed has been a debatable subject. Other experts argue that the tribe has only been formed in the 19th century.
Even after they were formally recognised as an ethnic group of the population in Jakarta by the 1930s, internally, the tribe did not unite as one rather identifying themselves based on the places they lived like Orang Kemayoran, Orang Senen or Orang Rawabelong. To this day, there are still those who identify themselves by that nature. Yet, the traditions that they held, although it may vary from places to places, are still somewhat the same.
You may want to know some of their most popular traditions here:
Keroncong Tugu: http://kratonpedia.com/article-detail/2015/4/26/555/Keroncong.Tugu.html
Tanjidor Music: http://kratonpedia.com/article-detail/2015/3/17/442/Tanjidor.Music.html
Rumah Kebaya: http://kratonpedia.com/article-detail/2015/3/14/437/Rumah.Kebaya.html
Lenong Denes: http://kratonpedia.com/article-detail/2015/4/7/509/Lenong.Denes.html
Delman Hias: http://kratonpedia.com/article-detail/2015/4/12/515/Delman.Hias.html
Pencak Silat: http://kratonpedia.com/article-detail/2015/3/5/421/Pencak.Silat.html
References:
http://www.infobudaya.com/wisata/betawi/9-mengenal-betawi.html
