In this task, you're given a context, further information available on a particular linked term from the statement, and an answer term. Your job is to generate a question that can use the information provided to obtain the given answer. You should use the information on both context and link information to create the question. Note that the answer to the question should be exactly the given answer, and if the answer is none, the answer to the question shouldn't be obtainable from the context or linked information.

Context: When Boris I assumed the throne of Bulgaria in 852, the country was still pagan, with the ruling Bulgar elite being Tengriists while the Slavic population practised its own religion. Link Information: the Slavs believed in a single heavenly God begetting all the lesser spirits governing nature, and worshipped it by their means. Answer: a single heavenly God begetting all the lesser spirits governing nature
What were the main beliefs of the religion that the Slavic population practiced in 852?