Gnomes

Gnomes keep the least contact with humans. 1500 years ago they had zero contact, and used their magic to keep from sight whenever possible. However at that time an incredibly amiable dwarf named Devlin was travelling the lands. For a time he made a living putting humans in a magic sleep and carrying them under the Gnome Mountains as a means of fast transit. However he found the whole secrecy matter cumbersome and made a heroic effort to introduce the two races for the first time. This was a magical milestone in the history of Gorum and the city of Pred was renamed after him. Trade in the newly renamed city of Devlin exploded and a mass trade route was established under the Gnome Mountains between Devlin and Cherie. The powerful Merchant families of T'Tinna gave their wealth to the gnomes for many magical secrets. In fact Humans traveled from all across Gorum to trade with the gnomes, leading to an age of magical enlightenment.

Gnome Magic is slightly different. They can only cast one two different spells as a spell like ability 1/day. Speak with animals or invisibilty (working only against humans).

Gnomes will trade with humans and some life among them but yes most of them keep to their underground secrets and the trade routes do not grand access to the underground gnomes cities, just the other side of the mountains, the trade city of Cherie

Despite multiple attempts, human nobility has no contact with gnomish rulers, beyond trade the gnomes kings have little interesting in engaging in human affairs, wars, and alliances

Elves, Dwarves and Halflings have more engaged contact with gnomes, but only a few humans have seen the sparkling clockwork cities under the mountains, and only with good reason