Back playing AJE again after a break and having fun with the four emperors...

A quick question based on the screen shot linked below. I have an army outside Genua, controlled by the enemy, Otho in this case. I haven't conquered the town and the region is not next to any of my regions.
Yet the supply overlay suggests I have supply there. Why exactly? I understood that my supply comes from friendly towns and regions and from neighboring friendly regions when in enemy territory.
thanks
Tony
Screenshot:
https://photos.app.goo.gl/o7RGXnJ8tHyVGvVX2