Jenny wrote:

But IIRC the Sarrans had a prophecy about how people coming from the sky would destroy them-- even if Mellanby wanted contact, I doubt they were really wanting to meet the new neighbours :-).

CHEL: This is the day that was prophesied. The day our lore foretold. They will come from the sky to destroy us. They will burn the stars to light their way. We must be prepared.

He relates the prophecy to the new aliens, arriving in the aftermath of the Galactic War. Of course, it's possible that he cited it every time some aliens turned up (we know the Mellanbys had visitors, such as Justin), but his people might have got a bit sceptical after a while. (It's interesting that we *never* see the prophecy fulfilled - traditionally, these things do come to pass, so perhaps Servalan decided to launch a revenge attack to teach them how to be polite to visiting dignitaries.)

I'm sure the Sarrans would always have been very wary of alien arrivals, but that doesn't mean they couldn't have had preliminary negotiations when Hal arrived (and if that was 20 years ago, he might have negotiated with Chel's predecessor). If they did, it would seem that the negotiations broke down, reinforcing the fear of aliens and undermining anyone supporting a more conciliatory policy. At this point, they might have concluded that the Mellanbys were the vanguard of the aliens who would destroy them, but if they really thought they were so dangerous I can't believe it would have taken 20 years to eliminate them, if only by starving them out.

Checking the script again, Dayna says the Sarrans were a problem when her father first arrived, but now leave them alone. This could undermine my thesis, but I'm still prepared to argue for (a) preliminary negotiation (b) breakdown (c) intense skirmishing (d) stalemate (e) leaving each other alone, as Sarrans decide there's no immediate sign of their world being destroyed.