Note: This is a reposting of a review from Dragonsfoot with minor editing.
The Valley of the Hawks is only but the first instalment of the Hex Crawl Chronicles, a series describing different sub-settings (based on certain North American areas, according to the author). It is published by Frog God Games and written by John M. Stater (of whose NOD magazine both Melan and Bryce Lynch wrote a review). It uses the Swords & Wizardry Complete rules, but can be used with any old school D&D-esque system (for those who are interested: a Pathfinder version is also available).