Did British Empire and Tanzania exist in the same era?

Yes, the two civilizations both existed around 1961 CE.

Which lasted longer, British Empire or Tanzania?

British Empire lasted longer (414 years).

British Empire: Avrupa; Tanzania: Afrika

British Empire (1583 CE – 1997 CE) and Tanzania (1961 CE – present) lived in the same era.

The empire with the most extensive territory in history. It was referred to as "the empire on which the sun never sets."

United Republic of Tanzania · Africa

Did British Empire and Tanzania exist in the same era?: Yes, the two civilizations both existed around 1961 CE.
Which lasted longer, British Empire or Tanzania?: British Empire lasted longer (414 years).
Which regions did British Empire and Tanzania rule?: British Empire: Avrupa; Tanzania: Afrika