In 1625 Mapmaking is invented, my scouts have done some fine mapping so I manage to trade my map around and get WM, some cash and 3 techs.
My empire
171.42*KB
Sky's empire in the mist
47.82*KB
minimap
12.59*KB
My aim is to block the celtic expansion so I'm building outward in. After this turn it turned out I had 4 techs over sky, writing, literature, mysticism and IW. My guess: he's researching mathematics.
Turned out to be a good guess, he finished it the turn after this one and traded himself back in business. He now has all techs I have but I presume he got all techs in the game now. I'll have to wait a bit 17 turns to go to poly.