Pantaleon in Wikipedia
King Pantaleon reigned some time between 190 BCE - 180 BCE and is one of the most enigmatic of the Greek kings in Bactria and India. He was a younger contemporary or successor of the Greco-Bactrian king Demetrius, and is sometimes believed to have been his brother and/or subking. He was the first Greek king to strike Indian coins, peculiar irregular bronzes which suggests he had his base in Arachosia and Gandhara and wanted support from the native population.
The limited size of his coinage indicates a short reign. Known evidence suggests that he was replaced by his (probable) brother or son Agathocles, by whom he was commemorated on a "pedigree" coin. Some of his coins (as well as those of Agathocles and Euthydemus II) have another surprising characteristic: they are made of copper-nickel alloy, a technology that would not be developed in the West until the 18th century, but was known by the Chinese at the time. This suggests that exchanges of the metallic alloy or technicians happened between China and the region of Bactria.