The writer of the 1st-century CE
Periplus of the Erythraean Sea credited Hippalus with discovering the direct route from the
Red Sea to
Tamilakam over the
Indian Ocean by plotting the scheme of the sea and the correct location of the trade ports along the Indian coast.
Pliny the Elder claimed that Hippalus discovered not the route, but the
monsoon wind also called
Hippalus (the south-west monsoon wind). Most historians have tried to reconcile the reports by stating that knowledge of the monsoon winds was necessary to use the direct route, but the historian
André Tchernia explains that Pliny's connection between the wind and the navigator was based on common pronunciation: in the
Hellenistic era the name of the wind was written as
Hypalus, only in
Roman times the spelling
Hippalus came into use. The wind had already been known in Hellenistic times and had before been used by
Himyarite (Southern Arabian Semites) and Indian sailors to cross the Indian Ocean.
Significance To understand the importance of Hippalus' discovery we have to know that before him Greek
geographers thought that the Indian coast stretched from west to east. Hippalus was probably the first (in the West) to recognize the north–south direction of India's west coast. Only someone who has this insight will think crossing the
Arabian Sea might be a faster way to
south India than following the coastline. The use of Hippalus' direct route greatly contributed to the prosperity of
trade contacts between the
Roman province of Aegyptus and India from the 1st century BCE onwards. From
Red Sea ports like
Berenice large ships crossed the Arabian Sea to the
Malabar coast and
Muziris port,
Tamil kingdoms of the
Pandyas,
Cholas and
Cheras in present-day
Kerala and
Tamil Nadu. ==Legacy in science and literature==