[wongarsu]

According to [1] more like 6000-4000 BC for Europe. Granted, that's still before 1700BC.

From a cursory study of Wikipedia my rough summary would be: Europe used to be roughly divided in the "Western Hunter Gatherers" (WHG) and "Eastern Hunter Gatherers" (EHG). The WHG typically had dark skin, dark hair and blue eyes, the EHG were typically light skinned with brown eyes. Blond hair may have originated from EHGs in North Eurasia and spread from there. Around 6000 BC farmers from Anatolia (~modern Turkey) started moving into Europe, the EEF (Early European Farmers). Those were typically smaller than European hunter-gatherers, light skinned and dark haired. They migrated North, partially replacing the EHG and WHG, partially mixing with them, and in some places the EHG and WHG simply took up farming. But Easter Europe is less amenable to farming, meaning the dark-skinned WHG diminished the most while the light-skinned EHG and EEF became the dominant groups in Europe's genetic diversity

1: https://en.wikipedia.org/wiki/Early_European_Farmers#/media/...