NAP’s = Non-Aggression Pact, which means exactly what it implies.
RGST has NAP's with a few alliances in ikariam and as such it is considered unacceptable to show aggression towards members of those alliances and they're supposed to be nice to you (it's a two-way thing). In order to see the treaties this alliance has with others simply click on your embassy and on the left hand side there is a little box saying "Action". Inside said box is a clicky link that says (would you believe?) "Alliance treaties".
Should you be threatened by a member of an alliance that we have an NAP with please inform out diplomat (Kris) of it and he'll deal with the issue.