Dragonsteel refers either to the seven-book, unpublished series set on Yolen, the five-book main story arc of that series, or Dragonsteel Prime, which was written as part of Brandon Sanderson's Masters Thesis.
Dragonsteel has been called the prequel to the Cosmere. It takes place first chronologically and will feature the Shattering, Hoid's backstory, and dragons. One reason Brandon has not prioritized this series, though, is that he doesn't want readers to feel that they have to read his other books in order to understand what is happening, and he probably won't publish Hoid's story until it becomes relevant.
The first two books of the 'Dragonsteel' series are The Liar of Partinel and The Lightweaver of Rens. These are considered separate from the main Dragonsteel story arc, and occur several hundred years prior. In these books, we will see how magic operated before the Shattering.
”Dragonsteel is an unpublished series set on the Shardworld Yolen. The first two books form a duology, with Hoid as a major character. They are preliminarily titled "The Liar of Partinel" and "The Lightweaver of Rens". The first one, and perhaps the second one as well are set before the Shattering of Adonalsium. Brandon will not show anyone these books, and I don't think he's even written them both. There are five more books that occur hundreds of years later, so not "directly" a series, but still the same world. These five are the core Dragonsteel sequence, the first of which Brandon wrote for his master's thesis at BYU. It is still in the library there. Many things have changed since then, so this book is no longer canon.
- Briefly mentioned Dragonsteel
— Theoryland - 2009-6-20
- Where in the universe does Dragonsteel take place?
— Theoryland - 2014-9-4
- When will we hear Hoid's story?
— Theoryland - Nov 8, 2011
- We have yet to see a dragon from you
— Theoryland - 2014-3-29
- Rewriting Dragonsteel
— Theoryland - Nov 8, 2011
- Brandon's answer to Peter
— Timewasters Guide forum - 2008-10-20
- Before Adonalsium was shattered, was there magic in the Cosmere and what form did it take?
— Theoryland - 2012-09
- Another Long and Rambling Post™ on Future Books
— Brandon's blog - 2010-10-12
- Windrunner's post
— 17th Shard forums - 2013-01-20
|Shards||Cultivation · Devotion · Dominion · Endowment · Honor · Odium · Preservation · Ruin · Bavadin's Shard · Survival Shard|
|Planets||Ashyn · Braize · Nalthis · Roshar · Scadrial · Sel · Taldain · Threnody · Yolen|
|Terms||Adonalsium · Sliver · Splinter · Realmatic Theory · Intent · Focus · Investiture · Shardpool · Spiritweb|
|Other||Hoid · Seventeenth Shard · Chronology · Shattering · Worldhopping · Letters|