Here is the descr_sm_factions file which I messed around with. Go ahead and test it out for me, but make sure to get backups.
So far so good. Playing as Norv. and just took Russia's last settlement, which activated the horde script. They became a people in flight, and shortly afterwards their horde army took a Mongol settlement!
France has also taken out Denmark. Making them horde as well and after some turns of wandering about the Denmark horde has finally decided to siege a Cuman castle.
This is just what I wanted. No more destroyed factions too early in game. I forget what turn/year this campaign is in, but I gather it is mid way finished and the best thing about it is that not a single faction is destroyed yet.
I did change The Moor Horde a bit though; I found it more reasonable that the horde unit didn't consist of Christians, that wanted to bring back a Muslim nation.
From:
horde_min_units 10
horde_max_units 20
horde_max_units_reduction_every_horde 10
horde_unit_per_settlement_population 250
horde_min_named_characters 2
horde_max_percent_army_stack 80
horde_disband_percent_on_settlement_capture 0
horde_unit Dismounted Christian Guard
horde_unit Dismounted Christian Guard
horde_unit Tuareg Camel Spearmens
horde_unit Tuareg Camel Spearmens
horde_unit Granadine Jinetes
horde_unit Chrisitan Guard
To:
horde_min_units 10
horde_max_units 20
horde_max_units_reduction_every_horde 10
horde_unit_per_settlement_population 250
horde_min_named_characters 2
horde_max_percent_army_stack 80
horde_disband_percent_on_settlement_capture 0
horde_unit ME Peasant Crossbowmen
horde_unit ME Peasant Crossbowmen
horde_unit ME Spear Militia
horde_unit ME Spear Militia
horde_unit Dismounted Tuareg
horde_unit Dismounted Tuareg
horde_unit Tuareg Camel Spearmens
UPDATE: it is year 1278. Silly me had an assassin that was doing nothing, tail the Russian King and shortly succeeded in killing the King in the newly captured Mongol settlement, so Russia is now officially destroyed. I found it weird that even after losing their last settlement before, their two vassals Poland and Hungry, remained vassals until I "accidentally" killed the Russian King and destroyed the faction. By that time Poland and Hungry were stronger than their protectorate, each having 5, and 4 settlements respectively of their own. Good news though, now that Russia is gone, Poland and Hungry once again became aggressive and began taking settlements of their own.