Greek and Turkish

I took it for granted that until a few centuries AD the Turkic peoples
lived way far to the east in Central Asia totally out of reach and
linguistic contact and consideration by Europeans. But in a Turkish
grammar I was surprised to find Turkish cases `-da' and `-dan' with
similar meanings to the Classical Greek suffixes in `oikothi' = "at
house" and `oikothen' = "from house". Is this a coincidence, or what?