In the 4th century, the Romans were increasingly under attack by Germanic tribes.
They joined islands on the Seine together to form one island - today's Ile de la Cité.
Most Roman buildings on the Left Bank were dismantled and their stones used as fortifications.
A notable attack was in 451 AD when Attila the Hun and his army advanced on Paris.
The legend goes that a majority of Parisians were persuaded to stay by a local noblewoman, Genevieve.
The Huns diverted their attack, Paris was saved, and Sainte Genevieve later became the patron saint of Paris.
The pressure of the attacks was so intense that Paris finally surrendered to Frankish king Clovis.
Clovis made Paris his capital and built an abbey on the hill, the Abbaye Sainte Geneviève, in which he was buried with Sainte Geneviève.
You can still see one of its towers in today's Lycée Henri IV.
The neighbourhood is full of references to this period : rue Clovis, rue Clothilde (Clovis' wife), rue Clotaire (their son), Sainte Geneviève Library, the Montagne Sainte Geneviève...
The Frankish Empire became the largest kingdom in Western Europe.
The word Frank gave rise to the name France and the name Clovis evolved into the name Louis - which became the name of 18 French kings!