There is a close affinity between the aboriginal tribes of Sumatra and the Sakais of Malakka, so well studied by a long series of English authors. From the long list of eminent works about these interesting peoples I can cite only a few of the most important. A complete bibliography is to be found in the standard work of Skeat and Blagden, The Pagan Races of the Malay Peninsula, which can be regarded as an encyclopædia on this matter.