What manuscripts did people use to create the NIV and KJV? Are the manuscripts used to fashion the NIV older than those used for the KJV?

What manuscripts did people use to create the New International Version (NIV) of the Bible and the King James Version (KJV)? Are the manuscripts used to fashion the NIV older than those used for the KJV? Are they the same manuscripts? To elaborate more on my question; I basically am interested in knowing what manuscripts or ancient documents were used when authors were putting together the NIV Bible, and when are those documents dated to? To follow on my elaboration above, the same question goes for the KJV Bible. I'm thinking that the question of reliability of version(s) is irrelevant if one was fashioned by older documents than the other. Though I still find major problems with reading things like "thou houth shalteth" in the year 2016. Thanks for your time.