I've posted this web site before, but it seems germane to post it again on this thread:

http://www.albanach.org/

Matt is the curator of the Scottish Tartans Museum in Franklin, North Carolina.

Check out the article entitled "Pre-Culloden Tartans", as well as the other articles -- very good research & advice.

A point of clarification: the Chief didn't necessarily determine the tartans in "ye olde days"; more likely, it was the women of the village, clan, etc. that did, because they were the ones producing it. You'll see quite a few paintings of Chiefs wearing tartan that looks nothing like the "clan tartan" for that clan today.

Case in point: in 1815, the Chief of the MacDonalds, Lord MacDonald, received a request from the Highland Society of London asking for his "clan tartan:. LMcD wrote back with the reply:

Being really ignorant of what is exactly The MacDonald Tartan, I request that you will have the goodness to exert every Means in your power to obtain a perfectly genuine pattern, such as will warrant me in authenticating it with my arms.
From: "Tartans" by Blair Urquhart

Cheers,

T.