The foreign accounts supplement the indigenous literature. There is no mention of Alexander’s invasion in Indian sources; we come to know about his exploits from Greek sources. The Greek writers mention Sandrokottas (identified with Chandragupta Maurya), a contemporary of Alexander.
This has served as the sheet-anchor in ancient Indian chronology, as we place the accession of Chandragupta around 322 bc.
A precise account of interior India is first obtained from an account by Megasthenes, Seleucus’ envoy to the court of Chandragupta Maurya, which has been preserved only in fragments quoted by subsequent classical writers like Arrian, Starbo and Justin.
These fragments, when read together, furnish valuable information not only about the administration but also about social classes and economic activities in the Mauryan period.
Greek and Roman accounts of the first and second centuries all mention many Indian ports and enumerate items of trade between India and the Roman Empire.
The Periplus of the F.rythrean Sea (by an unknown author, ad 80 115) and Ptolemy’s Geography (ad 150)-both written in Greek-provide valuable data for the study of ancient geography and commerce. Pliny’s Naturalis Historia (first century ad) in Latin describes trade between India and Italy.
Chinese accounts have proved a valuable source for information on the Gupta period and the years immediately following the end of Gupta rule.
The Chinese travellers, Fa-hsien (Record of the Buddhist Countries) and Hsuan Tsang (Buddhist Records of the Western World) who came to India to visit Buddhist shrines and study Buddhism, describe the social, economic and religious conditions of the country in the fourth-fifth and seventh centuries respectively.
Hwuili’s Life of Hsuan Tsang, and Itsing’s A Record of the Buddhistic Religion as Practised in India and Malay Archipelago, which refers to Sri Gupta, is valuable for studying North India in the 7th century ad.
The accounts of Arabs such as the merchant Sulaiman who visited India during the time of Bhoja (ad 851), Abu Zaid, Abul Qasim (died ad 1070) who authored Tubaqat ul-Umam, a book on ancient Indian culture and science, Shahriyar, Ibn Batuta and Ibn Nazim are valuable sources for the study of ancient Indian history.
In constructing the history of medieval and British periods, we are amply helped by the various extant architectural remains, historical books, letters, diaries, etc.