great library

[Eyn]

if a tribe build the great library
is there a way to stop learning "no, no" tech that
an other tribes have ?
...to stop learning tech other tribes allready have

[Gothmog]

I assume that what you say happens with the Great Library occurs when two other tribes make contact and trade the no-no advances. The only way I can think of to stop this is to block contact by using the negotiation event trigger. Unfortunately this stops all contact between tribes. This is only desirable if you want tribes to be perpetually at war or peace.