Dagobah was chosen by Yoda to hide from the Emperor until the chosen one came. it was also one of the 38 systems erased from the Jedi archives. For two decades he stayed there living in a simple mud hut, shielded from the Emperor's mind by a dark side cave--energy left by from a Dark Jedi from Bpfassh. Yoda trained Luke in 3 ABY, but the age-old master died less than a year later at the age of 900.
It has been described as a 'slimy mudhole' filled with steamy humidity, stinging bugs and swamps, which is why not many humans have been there. For those who have, they didn't last long.
The planet was used to hold a military intel outpost after the fight at Endor met a quick end. and since then no attempts to make settlements. So instead it has become a pilgrimage for those in the new Jedi Order to activate Force-inspired vision quests.