The Greco-Bactrian Kingdom was the eastern-most tip of the Ancient Greek world. It lasted between 250-125BC. It covered Afghanistan but also bits of Turkmenistan, Iran, Pakistan etc. It covered ground originally conquored by Alexander the Great.
The National Museum of Afghanistan has put on a touring exhibition which has been to the British Museum but also to France, Germany and the Netherlands. Much other archeology is on display in the Hermitage Museum in St. Petersburg, Russia.