Thennla is a fantasy setting for the Mythras game system. Encircled by the Outer Ocean, watched by the God of the Sun and the Goddess of the Moon, Thennla's continents reveal themselves. The jungles of Jandekot; the vast deserts of Rasputana; and there, in the east, the Moon Goddess Jekkara anchored over it, is Taygus, land of plains and hills, the great inland sea and teeming civilisations. Here empires are born: Korantia, fading now, but defiant, its city-states each a goddess incarnate; the Jekkarenes, oldest of all civilisations, and blessed by the Moon Goddess; and now the Taskan Empire, overturning centuries of tradition with new ideas, ruled by a god-emperor and his avatar, the Iron Simulacrum. And watching closely is Assabia, a land of cruel rites and cunning sorcerers. The World of Thennla sourcebook is available as a paperback (or as a free PDF) resource for Mythras - a campaign world that is open for exploration and adventure. It includes an overview of the world, centering on Taygus, and describes the magic of the place, and how to create Thennlan characters. More information is given in the supplements Shores of Korantia and The Taskan Empire, but this is an ideal introduction for Games Masters and players who want a magic-rich world of high adventure, with the flavours of classical Greece, Rome, Persia and Byzantium. The Thennla sourcebook will get you started and wanting to learning more. It will inspire you to create your own adventures and develop the cultures outline in its pages.If you already have Shores of Korantia or The Taskan Empire, this booklet is not essential, although it may prove a useful gazeteer for players.