Gundan robots were covered in thick metal armour. After being stuck in the white void for centuries, they were trapped in the void between the time-lines of when Tharils were free and when they became slaves.
Gundans could also walk the timelines and were not affected by the time winds. They travelled through the Gateway to the Tharil empire in the past, killing them and destroying their empire. This allowed the humans to enslave the Tharils and use their time sensitivity. (TV: Warriors' Gate)