According to Basu et al. 2016, further analysis revealed that the genomic structure of mainland Indian populations is best explained by contributions from four ancestral components. In addition to the ANI and ASI, Basu et. al (2016) identified two East Asian ancestral components in mainland India that are major for the Austro-Asiatic-speaking tribals and the Tibeto-Burman speakers, which they denoted as AAA (for "Ancestral Austro-Asiatic") and ATB (for "Ancestral Tibeto-Burman") respectively. The study also infers that the populations of the Andaman Islands archipelago form a distinct ancestry, which "was found to be coancestral to Oceanic populations" but more distant from South Asians.