From another thread, I've done a bunch of science around ensuring a DEAD dwarven civ, so here it is.
This worldgen..
Created in DF v0.42.04.
[WORLD_GEN]
[TITLE:DEAD_DWARVEN_CIV]
[SEED:UeiAe2y4QIkMGYS46IwO]
[HISTORY_SEED:EgI2OGYwKCIkwMC0uoKk]
[NAME_SEED:icIGQ22OUaEgYWseGOEG]
[CREATURE_SEED:csA0S2MaAycE60YYwQGg]
[DIM:17:17]
[EMBARK_POINTS:2500]
[END_YEAR:1000]
[BEAST_END_YEAR:1000:-1]
[REVEAL_ALL_HISTORY:1]
[CULL_HISTORICAL_FIGURES:1]
[ELEVATION:100:310:0:0]
[RAINFALL:1:1:0:0]
[TEMPERATURE:50:50:0:0]
[DRAINAGE:0:100:50:50]
[VOLCANISM:0:0:0:0]
[SAVAGERY:0:0:0:0]
[ELEVATION_FREQUENCY:1:1:1:1:1:1]
[RAIN_FREQUENCY:1:1:1:1:1:1]
[DRAINAGE_FREQUENCY:1:1:1:1:1:1]
[TEMPERATURE_FREQUENCY:1:1:1:1:1:1]
[SAVAGERY_FREQUENCY:1:1:1:1:1:1]
[VOLCANISM_FREQUENCY:1:1:1:1:1:1]
[POLE:NONE]
[MINERAL_SCARCITY:1000]
[MEGABEAST_CAP:0]
[SEMIMEGABEAST_CAP:0]
[TITAN_NUMBER:0]
[TITAN_ATTACK_TRIGGER:0:0:0]
[DEMON_NUMBER:60]
[NIGHT_TROLL_NUMBER:0]
[BOGEYMAN_NUMBER:0]
[VAMPIRE_NUMBER:0]
[WEREBEAST_NUMBER:0]
[SECRET_NUMBER:0]
[REGIONAL_INTERACTION_NUMBER:0]
[DISTURBANCE_INTERACTION_NUMBER:0]
[EVIL_CLOUD_NUMBER:0]
[EVIL_RAIN_NUMBER:0]
[GENERATE_DIVINE_MATERIALS:0]
[GOOD_SQ_COUNTS:0:0:0]
[EVIL_SQ_COUNTS:0:0:0]
[PEAK_NUMBER_MIN:0]
[PARTIAL_OCEAN_EDGE_MIN:0]
[COMPLETE_OCEAN_EDGE_MIN:0]
[VOLCANO_MIN:0]
[REGION_COUNTS:SWAMP:0:0:0]
[REGION_COUNTS:DESERT:0:0:0]
[REGION_COUNTS:FOREST:0:0:0]
[REGION_COUNTS:MOUNTAINS:0:0:0]
[REGION_COUNTS:OCEAN:0:0:0]
[REGION_COUNTS:GLACIER:0:0:0]
[REGION_COUNTS:TUNDRA:0:0:0]
[REGION_COUNTS:GRASSLAND:0:0:0]
[REGION_COUNTS:HILLS:0:0:0]
[EROSION_CYCLE_COUNT:1000]
[RIVER_MINS:0:0]
[PERIODICALLY_ERODE_EXTREMES:0]
[OROGRAPHIC_PRECIPITATION:0]
[SUBREGION_MAX:5000]
[CAVERN_LAYER_COUNT:1]
[CAVERN_LAYER_OPENNESS_MIN:1]
[CAVERN_LAYER_OPENNESS_MAX:1]
[CAVERN_LAYER_PASSAGE_DENSITY_MIN:0]
[CAVERN_LAYER_PASSAGE_DENSITY_MAX:0]
[CAVERN_LAYER_WATER_MIN:52]
[CAVERN_LAYER_WATER_MAX:52]
[HAVE_BOTTOM_LAYER_1:1]
[HAVE_BOTTOM_LAYER_2:1]
[LEVELS_ABOVE_GROUND:10]
[LEVELS_ABOVE_LAYER_1:16]
[LEVELS_ABOVE_LAYER_2:2]
[LEVELS_ABOVE_LAYER_3:2]
[LEVELS_ABOVE_LAYER_4:2]
[LEVELS_ABOVE_LAYER_5:3]
[LEVELS_AT_BOTTOM:2]
[CAVE_MIN_SIZE:1]
[CAVE_MAX_SIZE:1]
[MOUNTAIN_CAVE_MIN:0]
[NON_MOUNTAIN_CAVE_MIN:0]
[ALL_CAVES_VISIBLE:0]
[SHOW_EMBARK_TUNNEL:2]
[TOTAL_CIV_NUMBER:12]
[TOTAL_CIV_POPULATION:100]
[SITE_CAP:0]
[PLAYABLE_CIVILIZATION_REQUIRED:1]
[ELEVATION_RANGES:0:0:0]
[RAIN_RANGES:0:0:0]
[DRAINAGE_RANGES:0:0:0]
[SAVAGERY_RANGES:0:0:0]
[VOLCANISM_RANGES:0:0:0]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:310:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
Creates a dead dwarven civ, so when you embark, all you get are the two hardcoded migrant waves, and no other contact. No liaisons, no caravans, nothing. You are on your own. Also, positions like monarch or baron are not selected. You can remove the seeds and get similar worlds, of course. However, during worldgen, you'll have the greatest chances of the dwarven civ being DEAD if the fortress is conquered within the first 50 years, so watch for that during worldgen. No editing of raws is required, this works in vanilla DF.
The way this works is that there are a LOT of goblins in the world (over 100,000), apparently so many that they repeated siege and pillage the initial mountainhome sometimes 50, 80 or more times, to the point where the civ is considered dead. The elevation PSV ensures only a single, initial dwarven civ. If more than one dwarven civ is placed, it's unlikely the Dwarven civ will be dead.
I've been looking for a way to do this for a very long time, for community challenges, so I'm quite pleased with the results. Special thanks to PatrickLundell for finding a single dead dwarven civ from which I was able to reverse the relevant parameters.