“The original purpose of this dimension is unknown, however, according to legend, it was a precursor to The Overworld (citation needed). It has plain dirt and trees(?) made of clay. There isn’t really a reason to travel here unless you want to farm clay. Its portal is made of Red Glazed Terracotta.” - The Dimensional Almanac
The Interlopers don’t exactly know what the purpose of this dimension is. It was once a parallel dimension to the Overworld.
This dimension doesn’t have too much gameplay purpose, except for more clay.
{Picture} {Igniter Recipe}