You do not have to have contact with them *at the time of construction.* You only need contact with them before the GLib goes obsolete. In the hypothetical, the reason you didn't get construction from the Iros when the Indians bought it was because you did not know India. If the Iros have it and *either* the Aztecs *or* the French learn it, *or* you make contact with India, you get Construction. As long as the GLib is not obsolete, you can keep getting techs. Edited to add: If I'm in a game in which I build the GLib (other than an AW game), I build lots of boats, so that I can make contact with as many civs as possible. If 2 civs on the other continent that I know learn a tech, hey, that's a freebie that I can trade around at home!