<Li> Vedic Sanskrit (c. 1500--500 BC). This language is unique in that its source documents were all composed orally, and were passed down through oral tradition (shakha schools) for c. 2,000 years before ever being written down . The oldest documents are all in poetic form; oldest and most important of all is the Rigveda (c. 1500 BC). </Li> <Li> Mycenaean Greek (c. 1450 BC) and Ancient Greek (c. 750--400 BC). Mycenaean Greek is the oldest recorded form, but its value is lessened by the limited material, restricted subject matter, and highly ambiguous writing system . More important is Ancient Greek, documented extensively beginning with the two Homeric poems (the Iliad and the Odyssey, c. 750 BC). </Li> <Li> Hittite (c. 1700--1200 BC). This is the earliest - recorded of all Indo - European languages, and highly divergent from the others due to the early separation of the Anatolian languages from the remainder . It possesses some highly archaic features found only fragmentarily, if at all, in other languages . At the same time, however, it appears to have undergone a large number of early phonological and grammatical changes which, combined with the ambiguities of its writing system, hinder its usefulness somewhat . </Li> <P> Other primary sources: </P>

The origin of english as an indo-european language