Which preposition to use with troas

on Occurrences 1%

Having preached the word in these parts with considerable success, he and his companions wished to have gone into the proconsular Asia, and afterwards assayed to go into Bythinia; but begin forbidden of the Holy Ghost, who seems to have had a special design of employing them elsewhere; passing by Mysia they came down to Troas on the sea-coast.

Which preposition to use with  troas