In a letter (#172) written to Tevis Clyde Smith, circa August 1931 we learn:

Then Farnsworth asked to see it again, when he accepted my “The Sowers of the Thunder” for Oriental Stories. In his latest letter he accepted it for $40. Not much money, but in this case I wasn’t really thinking about the money and he could have had the story for nothing, if he’d made me that proposition. I’d have given it to him free, just to get it in print. Now I’ve got to get hold of something on the Big Tatar and try to pound out a novelet; I’ve been thinking of writing a tale about him for a long time. And Babar the Tiger who established the Mogul rule in India — and the imperial phase in the life of Baibars the Panther, the subject of my last story — and the rise of the Ottomans — and the conquest of Constantinople by the Fifth Crusade — and the subjugation of the Turks by the Arabs in the days of Abu Bekr — and the gradual supplanting of the Arab masters by their Turkish slaves which culminated in the conquest of Asia Minor and Palestine by the Seljuks — and the rise of Saladin — and the final destruction of Christian Outremer by Al Kalawun — and the first Crusade — Godfrey of Bouillon, Baldwin of Boulogne, Bohemund — Sigurd the Jorsala-farer — Barbarossa — Coeur de Lion. Ye gods, I could write a century and still have only tapped the reservoir of dramatic possibilities. I wish to Hell I had a dozen markets for historical fiction — I’d never write anything else.

The story that was accepted for $40 was 'The Thing on the Roof'.

'Sowers' is referred to in a letter (#173) to HPL:

Thanks for commenting on my energy in writing — but honestly, I’m provokingly indolent. I work in bursts and spurts. I may turn out a month’s output in a few days, and then loaf for weeks. I sell so little, though, that I have to produce a great deal in order to make a living at all. Just before Mr. Wright left on his vacation he took a long story for Oriental’s, which he had requested — a yarn dealing with Baibars the Panther. The readers seem to like my historical tales, for some reason or other, and I’m duly grateful, for I love to write historic fiction, puerile though my efforts may be.

Another letter to Tevis Clyde Smith (#195) written in March 1932, gives us:

Glad you liked the Roof business and the Sowers stuff. I’ve had quite a few praises on the Sowers thing, but don’t know whether they’ll get into the Souk. Likely not.

And again to HPL (letter #203) from April 1932:

By the way, Wright thought well enough of my yarn, “The Sowers of the Thunder” published in the current Oriental Stories, to advertise it in Asia. It deals with Baibars the Panther, and the overthrow of the last Christian army in Outremer: a magnificently dramatic historical episode which I fear I have failed by a long way to do justice. I’ll swear, I’ve written of Christian armies being defeated by Moslems until my blood fairly seethes with rage. Some day I must write of the success of the earlier Crusades to gratify my racial vanity.

To Tevis again (letter #204) circa May 1932:

By the way Farnsworth advertised my Baibars yarn in Asia which, I guess, is about as near the smooth papers as I’ll ever get.

Yet another to Clyde Smith (letter #206), circa May 1932:

Did you notice what a hand I got in The Souk on “The Sowers of the Thunder”? I’m sincerely amazed. I knew it was a pretty good yarn, but I didn’t have any idea the readers would go for it like they seem to have done. There must be more folks interested in historical episodes than is generally thought. Kirk Mashburn, a damned good writer, wrote and told me I should have sold it to Adventure — of which he says he hasn’t missed a copy since he found one in a deserted stretch of Florida Everglades many years ago. But if I’d sent it to Adventure, they’d have returned it unread, same as usual. Anyway, Farnsworth suggested the story and asked for it.

And to Lovecraft on 24th of May, 1932 (letter #208):

If you haven’t already obtained a copy of Oriental Stories, containing my “Sowers of the Thunder”, I’ll be more than glad to lend you mine.