Complex sentence: One of the most important finds on Titelberg has been a huge number of Celtic coins which come from not only the Treveri themselves but also several other Celtic tribes, indicating that this had become a centre of trade and commerce showing signs of urbanization.
Split into simpler sentences: One of the most important finds on Titelberg has been a huge number of Celtic coins which come not only from the Treveri themselves but from several other Celtic tribes. This indicates that it had become a centre of trade and commerce showing signs of urbanization.