Memory, Sorrow and Thorn

Description

(from wikipedia:)

The books are set on the continent of Osten Ard, whose inhabitants include Sithi (elf-like immortals), Qanuc (troll-like mountain-dwellers), and other races, as well as several distinct human nations. The youthful conquests of King John the Presbyter (also called Prester John) united most of the human world into a single realm, but by the beginning of the first book, the former conqueror is too old and feeble to stop his sons from quarrelling. As the conflict widens throughout their world and beyond, a young orphan struggles to understand enough of it to survive.