Hello Mykeris,
I also don't think that it could be Batak, most of the Batak are christian (but not all), the sheat have some affinitys to Aceh. Why do you think it coudn't be Minangkabau? I don't think that it could be javanese but maybe a other option is Lombok?
BTW, it is the wrong place in Keris Warung Kopi.
sajen