Guild Wars 2

as the title says above how do ifarm to get those group effort anchievements to get heirloom bags

rescue civillians

Reading the patch notes also helps.
“Rescue enough citizens and work together with the entire map to earn five tiers of rewards.

As players surpass each tier, contributors are rewarded Spinal Shards, Refugee’s Belongings, and Found Heirlooms.
Tiers are set at 100, 300, 600, 1000, and 1500 citizens rescued."

You should not have to read the patchNotes for this kind of information…