Generally in the SCA, the term “early period” refers to things dating between 1100 and 1400 or anything earlier than that. (Yes, it’s a vague term and “early” changes depending on what geographic location you’re talking about. But, that’s okay.)
Here are a couple of links that focus on early period “viking” construction. Check out the blogs/vlogs and sites for inspiration.
I have a couple of Norse garb links!https://www.cs.vassar.edu/~capriest/vikresource.html (includes info on trim patterns and weaving)https://sites.google.com/site/archoevidence/home/viking-clothing-guides (links to articles on specific location/time period garb and accessories – this is an amazing resource if you have a defined Norse persona to kit up, but be prepared for perplexing auto-translate glitches)
A handy list of Irish garb resources: https://matsukazesewing.blogspot.com/2014/02/as-my-inaugural-post-i-have-decided-to.html?m=1
The blog has some nice projects, too, not just links. For example, this leine: http://matsukazesewing.blogspot.com/2017/06/whose-sleives-hang-trailing-down-almost.html
I have a couple of Norse garb links!https://www.cs.vassar.edu/~capriest/vikresource.html (includes info on trim patterns and weaving)https://sites.google.com/site/archoevidence/home/viking-clothing-guides (links to articles on specific location/time period garb and accessories – this is an amazing resource if you have a defined Norse persona to kit up, but be prepared for perplexing auto-translate glitches)