When did the Roman Empire fall (your thoughts)?

[starman2012]

Yes, Tours preceded the HRE, but the threat did not end afterwards. Clearly, Charlemagne felt the need to create the Spanish March.

I think the idea was to liberate as many christians as possible. The basques in that area are said to have been the last to submit to the authority of Rome and the first to throw off the yoke of the arabs.

Then the Umayyads established themselves in the Iberian peninsula for over 100 years and became a bigger threat given their expansionist bent.

But wasn't tours the muslim high water mark in western europe?

The Turks eventually reached the gates of Vienna - twice, I believe.

Sure 1529 and 1683 IIRC.