As someone who writes what I think of as “hard†fantasy — similar in purpose to “hard science fictionâ€, that is, with a strong emphasis on the possible — I research all the bloody time. I don’t believe you can make a working fantasy world in which most of the characters are human or human-like without a decent understanding of history or cultural source material — in this case, from our own pre-industrial past. The same problems always need to be solved, no matter the age — food, shelter, travel, trade, self-defense. Only the possible solutions change.

I wrote that and then Deb asked me to talk some more about hard fantasy. I’ve used the term for years and there’s even a Wikipedia page. My work is not mentioned, the calluses on my brain from my long (and lengthy!) labors unrecognized. Sigh. But the point is that the term, in general usage, means well-constructed, detailed works of imagination, usually with a lot of world-building involved.
For me the quest for hard fantasy inevitably begins with Tolkien. I loved the complexity of Middle Earth, its thousands of years of history, and the fact that the characters themselves were immersed in and shaped by that history. Depth is what hard fantasy is mostly about, and hardcore realities. What do people eat? How do they travel? How do they communicate? And — most importantly — how do the answers to those and a thousand other questions create a believable society and world?
What makes hard fantasy is the world itself. Characters may live in an entirely un-Earthlike setting, but I need their way of living to make sense. 
A good hard fantasy book not only works as a story, but generally makes the reader want to explore the new world. I wanted to wander through Middle Earth for years, with or without a compelling story. I still have fantasies of stumbling on Lothlorien in a forest, or turning a bend in a river and seeing the colossal royal statues that guard the Falls of Rauros.
There’s a whole other conversation we need to have about imaginary geography, which is another key factor, but I don’t have time for that here. Still, it’s very important for all the same reasons.

I have more to say about what makes hard fantasy, and my many influences: I’ve also given Deb a lot of material regarding the books that I consider the most essential tools for fantasy worldbuilding. All of it will appear in one form or another as we get closer to the publication of the new Osten Ard books.
But this is what I strive to do, because I love it. In the new books I’m back in my most developed world again, and adding tons of new details, helped immeasurably by readers who take the whole seriously and want to see me do it justice. I agonize over mileage. I worry about economic systems and political realities. I want my characters to exist as complete people in the middle of the only lives they’ve ever known. I sweat every detail, clothing, songs, folklore, history, class conflicts, technology. Because I want to know so I can sink into that world and live in it. And it seems that my most dedicated readers feel the same way. For which I am extremely grateful.
Cheers.
Tad

Deb here, adding a note about ‘The Last King of Osten Ard’. The first two books — ‘The Heart of What Was Lost’ and ‘The Witchwood Crown’ — are moving through their production schedules, and in the past few days, Tad and DAW Books and Michael Whelan have been pouring over Michael’s initial art.
We’re delighted to have Isaac Stewart now on board: he is map-maker to Brandon Sanderson. Isaac is at work on entirely new maps — I personally very much look forward to Tad’s visualization of Osten Ard being ‘told’ through another hand.
Also happening right now: the foreword from Tad for ‘The Heart’, and comprehensive Osten Ard appendices for ‘The Witchwood Crown’…
Onwards to January 2017.
Just finished MST for the forth time since I first delved into Osten Ard over 20 years ago (it goes too fast!).
To say I’m excited about the prospect of going back there is a massive understatement! But I am! Thank you sir! x