1. Have these affected animals moving from places to other places?
2. What animals lived in them?
3. How (or if) did they affect the growth of large kingdoms?
4. What impression might these, thousands of kilometers spanning lands, given to peoples from the steppes or places were forests were rarer (or not so old)?

What a good subject, I would have thought it would be of little interest to most. To me the European forests were a fascinating place. The forest cover invited plenty of rain so the biggest problem in going from A to B was crossing a network of marshes. Some may think the ancient Europeans were not very conservative with water. In fact the opposite was the case; they were great water conservationists even from Neothilic times. They soon learned to deal water quality rather than quantity and early on started irrigation control schemes to constantly drain the marshes and so make more living space, rather than live on sloping ground which of course was in the highest demand.

They had no such thing as a shortage of woods and yet many areas were held as sacred. The early inhabitants went through periods of slash and burn and so learned by their mistakes. However the same experience at the same time in the near East was different for lands were drying out with no more rains to come and therefore no more woods. The solid rains continued in Europe and so flooding was always a problem and added to their skill with water for which they became famed throughout the ancient world. 

 Another problem was the beaver that could mess up water schemes by randomly building dams that diverted important tribal water courses, so the people gained constant practice in waterway maintenance and practice in respecting the various tribes around them for fixing problems common to all and so began the mighty system of common law that is still with us. The beavers didn’t disappear from European environment until the 17^th century when a craze began for of hats made of beaver skin.  

A totally cleared area was found to be less profitable than one part woods and part fields. Birds were an important food source but no trees no birds nor wild pigs another delicacy. Nearly all early European village sites had pig bones in them. For many reasons an environmental attitude “let it be” became peculiar to the temperate zone of Europe although being a very active people with a passion for competitive sports. Their deeply conservative way of thinking became part of the early religion that developed as the numbers of dwellers within the green canopy grew. The softwood forests crossed within a two hundred mile band while the more northern climes had the hardwoods.