what was the religion followed by the people here?
Paganism and Christianity
Mercia
The conversion of Mercia to Christianity occurred in the latter part of the 7th century, and by the time of Penda's defeat and death, Mercia was largely surrounded by Christian states. 
who was wulfhere of mercia? King of Mercia which modern country is it a part of today? UNANSWERABLE name another king of this place. King Offa
wiki:11585751
Mercia [SEP] Mercian religion
Diuma, an Irish monk and one of Oswiu's missionaries, was subsequently ordained a bishop – the first to operate in Mercia. Christianity finally gained a foothold in Mercia when Oswiu supported Peada as sub-king of the Middle Angles, requiring him to marry Oswiu's daughter, Alchflaed, and to accept her religion.