By many the Salarians are considered the most intelligent species. The Slarians think , talk and move fast. To many Slarians they believe they are superior to other species esspecially Elcor and Krogan.Salrians are known for having many high-tech inventions. The Salarians have a based of political alliances and heritage like the nobal families in Mideval Europe.
The Salarians provivded the Krogan with advantaced technologies that the Krogan got greedy with and tried to use to conquer the galaxy creating the Krogan Rebellions. The Salarians then developed the genophage and gave it to the Turians to poison the Krogans at birth devastating their population numbers. Over time when the Krogans attempted to redeem themselves the Salarians gave the Krogans a cure for the geonphage however, the Salarian leader didn't trust them and asked Commander Shepard to deactivate the cure. The fate of the Krogan was up to him but, most likely favored the krogan to give them a second chance. Also Mordin sacrafices himself to make sure the geonphage is cured.