Slavery was most common in Africa, India, China, Europe, Japan, the Middle East, South America, North America, even Australia, Southeast Asia, and Micro- and Polynesia. Slavery has existed in every culture, on every continent (with the exception of Antarctica). It has no common region.
Blood group A is the most common bloodtype in Europe.
Catholicism is most common in Western Europe, predominately Southern (Portugal, Spain, and Italy).
The Southern region
fruit
The most spoken language in Europe is Russian, both by native and total speakers.
Giardiasis is most prevalent in Eastern Europe.
Swords
Europe
Christianity.
the Euro
Commercial farming.