There is no empirical evidence of the sort you desire for the condition of the earth a few thousand years ago, but there is tons of honest pure straight witness testimony.
There is secondhand eyewitness testimony, which is all any of the written testimony is.
There isn't even secondhand eyewitness testimony.
"Second hand eyewitness testimony" is what is generally referred to as hearsay evidence. It has a poor reputation for accuracy, and is usually not permitted in courts.