That depends on exactly which Greeks, and when, you're referring to. Of course, after Alexander's death, trade was increased on a massive scale. They traded in foodstuff, textiles, incense, timber, various metals, marble, spices, and so many other things. That doesn't include aspects of culture, language, law, et cetera.

Non-specific to exactly which Greek states, they traded with the Persians, Scythians, Carthaginians (Phoenicians), Romans, Etruscans, Thracians, Illyrians, Celts, Egyptians, et cetera.

I hope this helped you.