After the discovery of the Citadal, the Asari were reproducing at a faster rate because they were getting noticed by most other alian races. So to inhabit more off spring they needed to find planets to let the live on. 19 planets were found all by Asari exploration teams but the 20th planet was founded by two Asari mothers. Lady Corfan and Matriarch Vasir were two friends out exploring for suitable partners to help reproduce on the eve of of their Matron years but there transportation ship was shot down and their escape pod fell to a deserted planet.