Shalom

There is little doubt that the Gemara is referring to the Emperor Nero who ruled the Roman Empire during the years 54-68CE. The Jewish rebellion against Rome broke out in the year 66 (+), when Nero was Emperor. His reign ended before the Roman assault on Jerusalem.

This raises a major question. According to Roman historical sources Nero committed suicide in the year 68, while the Gemara states that he converted to Judaism and ran away. What really occurred here? Very possible that he disappeared during the war against the Jews leaving a will (as the Gemorah states) and thus was assumed to have committed suicide after vanishing with no trace.

Either way, no doubt the reference is to Nero, who appears a few times in the Gemara.

All the best.

Yehuda Landy