the celtic boii were thought to be an old austrian celtish group (although that's hard to prove due to a lsck of evidence) that lived in the area we today call bohemia and also conquered an etruscan city in northern italy that it renamed to balogna, and which became an important italian city in the roman and post-roman periods.

you won't find a lot of galatians today. they were just straight up gauls, like the gauls in other places in europe, but they were settled in turkey by the successors of alexander during the macedonian period. the galatians were so irish that their warlord, at about 280 bce, was named brennan. you could take their freedom..

however, the galatians/gauls/irish left huge traces in central anatolia. to begin with, they founded the city of ankara, which is today the capital of turkey (not constantinople). much of the local culture in the region of central turkey, including a lot of the musical culture, is not central asian (where the turks came from) in origin but celtic and western european in origin. that distinctive arabic pentatonic tonality in string music, and which is also present in celtic music, was brought to the area by the galatians, who became the folk people of the region, in contrast to the emperors in greece and persia and rome and mecca. they eventually assimilated into the kurdish and armenian populations.

the galatians are probably one of the primary sources of remnant red hair variability in central turkey, but you need to be careful. yes, there are red-haired turks. in fact, it's not that uncommon:

https://www.google.com/search?num=10&newwindow=1&sca_esv=7a9d3f4fa3fac4b8&sxsrf=APpeQnuoQjur4b7X-jKxtL9zsSOkX8X5_w:1791891284615&ei=VBfOavXsJKiQm9cPwOr4oAY&q=red+hair+in+turkey&tbm=isch&sa=X&ved=2ahUKEwj15vqb87aXAxUoyOYEHUA1HmQQ7Al6BAgYEAE&biw=1518&bih=734

this woman is a successful model and actress in turkey and if you think she looks pretty darn irish it's because she's likely galatian:

https://www.pinterest.com/aydanisayeva5/elcin-sangu/

however, the region was settled by an indo-european group called the hittites a very, very long time ago. the hittites were displaced by further waves of people from the steppes, and eventually assimilated into the greek world and then conquered by the persians and then the greeks and romans - all indo-european groups that would have had some red hair. 

but by the time of the arabs and turks, the galatians were all that was left of this, along with the armenian and kurdish groups, which were still developing identities. the galatians disappeared in the end, but there would have been a time when all of these other groups rode up into the mountains to live with the remnant, wild celts. they survived here longer than they did in austria, in spain or in france.