Ancients is a primarily group-content cycle of six events in Frontier Mountains. Each Ancient is spawned by an activity in the zone, and there are achievements for being in the zone to see each of the six awakened, and a further achievement for being in the zone to see all six ancients spawned in one hour.
Each Ancient other than Ancient Pinepeak can be killed for a group gear reward, and a group gear reward is given to everyone that receives the all in one hour ach too. These items can be combined with the raid drop Element of Kunark which will transform it into a raid-tier item.
EQResource has more detailed writeups of all events and links to the gear etc:
http://eok.eqresource.com/ancients.phpEvent breakdowns:Ancient Pinepeak, Guardian of the ThicketCollect "Enchanted Runestones" from Syldon stalkers which are near the Sarnak fort in the Northwest.
Turn in Enchanted Runestones to grove guardians which range east and north from the Druid rings to the Overthere zoneline.
After turning in approximately 30 Enchanted Runestones, there is a zonewide emote, and Syldon couriers start to spawn at the Sarnak fort, and run from there to the Overthere zoneline. They will not stop to fight, but can be snared, rooted, or mezed.
You must stop all the Syldon couriers from reaching the OT zone. After about 12 minutes, a zonewide emote will either indicate you failed if any couriers got past, or that you stopped them all. Success means that Ancient Pinepeak will spawn, and everyone in the zone will be buffed with Ancient Pinepeak's Blessing (1h, 2500hp/tick regen, +75% runspeed, and an 80k proc that I think is sarnak-specific)
Ancient Starcollector, Guardian of the PackIn NE area of the zone, every time 5 wolves are killed a frontier starhowler spawns until there are 10 up.
Kill the 10 frontier starhowlers to spawn Ancient Starcollector.
Ancient Broodmother, Guardian of the BlightIn the SE corner of the zone, kill 30 drogan tamers, which will spawn ~35 highweb swarmers along the southern wall area of the zone.
Kill the swarmers to spawn Ancient Broodmother.
Ancient Denmother, Guardian of the CubsIn the SW areas, kill 50 bears to spawn the Ancient Denmother
(note: when killing the Ancient Denmother, she'll go down at 10% and Gerald the Obnoxious will spawn and run away. Chase him and say "loot" to make him fight you... he will drop the loot.)
Ancient Destroyer, Guardian of StrengthIn the east, there are some burynai legion pacifists (I think 4 of them). Say invader to them, and a series of invading brutes will attack them. You can hail multiple pacifists at the same time to spawn more brutes at once.
Kill the brutes to save 10 legion pacifists and spawn Ancient Destroyer
(note: everyone who hails Elder Gemhummer at the burynai cave entrance after this ancient dies will receive loot)
Ancient Whitehorn, Guardian of the StampedeKill 30 rhinoceroses in the central area north of the big fort to spawn Ancient Whitehorn
(note: he doesn't fight back and runs too fast to keep up with, and regens if not attacked regularly. He stops briefly in 5 locations though, so setting a person to fight him at each stopping spot is required.)
To complete The Foretold Hour achievement, I think it's best to work in approximately this order:
Get swarmers and starhowlers ready and collect enchanted runestones.
Start killing rhinos and bears and swarmers while turning in runestones and completing the Pinepeak event.
Once first ancient spawns, send a team to save the burynai pacifists and continue to work the kill-based spawns and the wolves. Kill the ancients last, after you've spawned them all and got the achievement.