In general, atheism is the lack of belief in a God or divine beings. Some people label it as non-belief in God.
Although some sort of religion has predominated virtually the entire world over the last five thousand or so years, there has been some atheistic presence in most places in most of recorded history.
As for the time before recorded history (known as prehistory), history scholars are uncertain as to whether humans were theistic or atheistic. One archeological finding of an ancient human buried in Iraq was found to have decomposed flower petals in the dirt surrounding the body. Researchers believe that the flowers were put there by others in some sort of formal burial process. Some archeologists point to this find to suggest that early humans might have followed rituals or religious practices, although the issue of early religions is still relatively unknown.