I was told on this board, somewhat recently, that the Manchus were merely one tribe or clan among many of the Jurchens.
I have been trying to get more information on this and flesh out my knowledge of their history and traditions and mode of dress, but information on the Manchus prior to the Qing Dynasty or on the Jurchens in any form is hard to find.

Anyone have any info to offer? Or can recommend any English language sources (I like maps, too)?

There are many Jurchens tribes; several Jurchen tribes was united and formed the Manchus and called themselves Qing (aka Cheung or Ching). Jurchens are came from Mohe tribes (aka Malgal). Basically made up with largely Nomadic herdsmen.

Jurchen and Mohe tribes are well known Tungusic tribes that roam around mostly Manchuria (now, NE China), Southern Siberia and Northern parts of Korean peninsula. They were frequently at war each others, and conflicts with Mongols, other Tungusic tribes, Qidans (Khitans), Koreans and Chinese.

General description-
Jurchen
http://en.wikipedia.org/wiki/Jurchen

Mohe
http://en.wikipedia.org/wiki/Mohe

Refer to these threads for more info:

http://www.chinahistoryforum.com/index.php?showtopic=25179
http://www.chinahistoryforum.com/index.php?showtopic=14615

"Sushen" people were the ancestors of all Tungusic peoples...