I have read in Northern Crusades [1] that in XII/XIII century forrests separating Prussia from Lithuania/Mazovia had been truly impassable (except for raiding parties - raizes) and the only campaining had been possible along large rivers. Lituanians had it easier because they had been bringing siedge equipment and canons downstream. So there is some change although meassured in centuries :)

[1] https://www.amazon.com/Northern-Crusades-Second-Eric-Christi...

Rubicon by Tom Holland - https://www.amazon.com/Rubicon-Tom-Holland/dp/1400078970

Christopher Browning, Ordinary Germans Reserve Police Battalion 101 and the Final Solution - https://www.amazon.com/Ordinary-Men-Reserve-Battalion-Soluti...

Zealot: The Life and Times of Jesus of Nazareth https://www.amazon.com/Zealot-Life-Times-Jesus-Nazareth/dp/0...

The Poison King: The Life and Legend of Mithradates - https://www.amazon.com/Poison-King-Legend-Mithradates-Deadli...

To End All Wars - https://www.amazon.com/End-All-Wars-Rebellion-1914-1918/dp/0...

The Northern Crusades - https://www.amazon.com/Northern-Crusades-Second-Eric-Christi...

The Fall of Constantinople 1453 - https://www.amazon.com/Fall-Constantinople-1453-Canto-Classi...

Lost Enlightenment: Central Asia's Golden Age from the Arab Conquest to Tamerlane - https://www.amazon.com/Lost-Enlightenment-Central-Conquest-T...

The Indian Ocean - https://www.amazon.com/Indian-Ocean-Seas-History/dp/04154453...

Indian Summer: The Secret History of the End of an Empire - https://www.amazon.com/Indian-Summer-Secret-History-Empire/d...