Economy and Trade in Hellenistic Southern Asia.

Very little is known about the economy of the Indo-Greeks, although it seems to have been rather vibrant. The abundance of their coins would tend to suggest large mining operations, particularly in the mountainous area of the Hindu-Kush, and an important monetary economy. The Indo-Greek did strike bilingual coins both in the Greek "round" standard and in the Indian "square" standard, suggesting that monetary circulation extended to all parts of society. The adoption of Indo-Greek monetary conventions by neighbouring kingdoms, such as the Kunindasto the east and the Satavahanas to the south, would also suggest that Indo-Greek coins were used extensively for cross-border trade.
It would also seem that some of the coins emitted by the Indo-Greek kings, particularly those in the monolingual Atticstandard, may have been used to pay some form of tribute to the Yuezhi tribes north of the Hindu-Kush. This is indicated by the coins finds of the Qunduz hoard in northern Afghanistan, which have yielded quantities of Indo-Greek coins in the Hellenistic standard (Greek weights, Greek language), although none of the kings represented in the hoard are known to have ruled so far north. Conversely, none of these coins have ever been found south of the Hindu-Kush.
The Indo-Greek kings in Southern Asia issued the first knowncupro-nickel coins, with Euthydemus II, dating from 180 to 170 BC, and his younger brothers Pantaleon and Agathoclesaround 170 BC. As only China was able to produce cupro-nickel at that time, and as the alloy ratios are exclusively similar, it has been suggested that the metal was the result of exchanges between China and Bactria. An indirect testimony by the Chinese explorer Zhang Qian, who visited Bactria around 128 BC, suggests that intense trade with Southern China was going through northern India. Zhang Qian explains that he found Chinese products in the Bactrian markets, and that they were transiting through northwestern India, which he incidentally describes as a civilization similar to that of Bactria: "When I was in Bactria", Zhang Qian reported, "I saw bamboo canes from Qiong and cloth (silk?) made in the province of Shu. When I asked the people how they had gotten such articles, they replied: "Our merchants go buy them in the markets of Shendu (northwestern India). Shendu, they told me, lies several thousand li southeast of Bactria. The people cultivate land, and live much like the people of Bactria". Sima Qian, "Records of the Great Historian", trans. Burton Watson, p. 236.
Maritime relations across the Indian ocean started in the 3rd century BC, and further developed during the time of the Indo-Greeks together with their territorial expansion along the western coast of India. The first contacts started when the Ptolemies constructed the Red Sea ports of Myos Hormos and Berenike, with destination the Indus delta, the Kathiawar peninsula or Muziris. Around 130 BC, Eudoxus of Cyzicus is reported (Strabo, Geog.  II.3.4)  to have made a successful voyage to India and returned with a cargo of perfumes and gemstones. By the time Indo-Greek rule was ending, up to 120 ships were setting sail every year from Myos Hormos to India (Strabo Geog. II.5.12).
Πηγη: https://en.m.wikipedia.org/wiki/Indo-Greek_Kingdom