Herodotus, Skylex and Ctesias were the early Greek writers (before the invasion of Alexander) who wrote about India. Herodotus and Ctesias received their understanding about India through Persian. According to Herodotus, North-West India was 20th satrapy of the Empire of King Darius. He wrote about the political conditions of North-West of India. His legendary book "Histories" furnishes a good deal of information about India and other countries. Skylax writes about his voyage between Persian Gulf and Indus Valley. After these early Greeks, some Greek historians like Nearchos, Aristobulus. Onesicritus Clitarchus etc., had companioned Alexander to India. These writers condensed into writings the experience of the wars which Alexander had crusaded. Without these writers, Alexander's crusade would have remained unknown to everybody. later comes the historians who arrived subsequent to Alexander's invasion. The most authoritative among these writers was Megasthenes, an ambassador of Seleukus, in the court of Chandra Gupta. His accounts are of rich historical value, because his writings are the result of first hand experiences. Deimachus was the ambassador in the court of Bindusara and had written about India. However, according to Strabo the account of Magasthenes and Deimachus are not dependable. He writes- "Generally speaking the men who have written on the affairs of India were a-set of liars. Deimachus holds the first place in the list, Megasthenes comes next,.…No faith whatever can be placed in Deimachus and Megasthenes". Strabo seems to be partially right, because even if these writers had not fancied things intentionally, their lack of knowledge in Indian languages was a hindrance to them. Furthermore, they witnessed every thing from the point of view of the Greeks. Therefore, Dr. R.C. Majumdar is just about the opinion that their accounts should be read with vigilance and wherever feasible, should be scrutinised and confirmed. Lastly comes the later Greek and Roman writers like Strabo, Diodoras, Arrian, Pliny, Ptolemy etc. These writers were more coherent and exceedingly decisive and their accounts are of profound value for the early history of India.