Simplify the following text for a Grade 6 native English-speaking person.
Original: Historians disagree about the dates of a `` Bronze Age '' in China . The difficulty lies in the term `` Bronze Age '' itself , as it has been applied to signify a period in European and Middle Eastern history when bronze tools replaced stone tools , and were later replaced by iron ones .
Simplified: The Bronze Age is the time period when people made tools from a metal called bronze .