Complex sentence: Later, Alexander founded a city on the site of the battle, which he called Nicaea; as of yet, this city has not been discovered, any attempt to find the ancient battle site is doomed, because the landscape has changed considerably.
Split into simpler sentences: Later, Alexander founded a city on the site of the battle, which he called Nicaea; this city has not yet been discovered. Any attempt to find the ancient battle site is doomed, because the landscape has changed considerably.