The faeren are an extremely short sub-race of humans that live underground in secret mounds called "barrows." Their males are chubby, but muscular, and are all capable of growing vast beards, looking similar to Tolkien's dwarves. Their women are regarded as beautiful and fair, usually sport long hair, and can be compared to Tolkien's elves. They have remarkable hair-growing abilities, hence their men having enormous beards and their women having hair that typically reaches to the floor. They have advanced technology, a little higher than what humans have today, except for the advent of the internet and digital devices.
I am wondering if it is possible for a people like this to be able to survive and have a large social and economical infrastructure living underground for many years without leaving to the surface?