Complex sentence: The Semelais are classified as Proto-Malays, one of three categories into which the Orang Asli are officially divided, although the Semelai language is an Austroasiatic language, while the other groups classified as "Proto-Malay" speak Austronesian languages closely related to Malay.
Split into simpler sentences: The Semelais are classified as so-called "Proto-Malays", one of three categories into which the Orang Asli are officially divided. Actually the Semelai language is an Austroasiatic language, while the other groups classified as "Proto-Malay" speak Austronesian languages closely related to Malay.