Did Tolkien even plan to fill in the other sections of Middle-earth?

[Juicy-Sweet]

Originally Posted by Zigûr

2) Leaving the details vague contributed to a sense of mystery which Professor Tolkien found appealing; see Letter 247 where he worries about publishing The Silmarillion because exploring the backstory of The Lord of the Rings might "destroy the magic, unless new unattainable vistas are again revealed." I think confining the details to the North-west is important for the same reason..

Indeed. The Sea of Rhun always fascinated me, ever since I first reat it 30 years ago. Its marked on the map as a huge lake with a name, but there's absolutely no information about it,

That and the two blue Wizards are among the things that fascinate me the most. It's strange really