Man has known of the Tarkin since the Second Era and yet they are not mentioned at all in their history. This is probably due to their seclusion and very limited interaction with them.
What is known about the Tarkin is mainly knowledge from the few explorers who have ventured into the Dead Lands. A few Tarkin have also been known to integrate themselves into human society, but they tend to be very secretive and after a while just disappear. Those who have met them would tell you that they are wise and very cautious and they seem to live off just fish.
Their physiology is comparable to humans but with several major differences. They are, on average, around four to five feet tall, have tusks on their lower jaw which grow throughout their lives and their skin is thick and leathery. They also have eyes which are either completely white or black.