The spring of 1348.
The black plague stroke Siena, Italy in 1348
There are many plausible answers to this question, asssuming there is agreement regarding the 'decline' of 'Italy.' One factor is the Black Death which swept much of the Europe between 1348-50 and killed apporximately 30-60% of the population.
Black plague
Between the years of 1348 to 1352 the bubonic plague swept through Norway. Killing almost everything it came in contact with. Norway lost 60% of its population during this time.
The factors of 1348 are: 1, 2, 4, 337, 674, 1348.
As of 2021, the population of Italy is around 60 million people.
The Black Death spread through Italy from south to north in 1348. In some places it remained as late as 1352. In the north of Italy, around Milan, the outbreak is said to have been not as bad or long as it was elsewhere.
italy
In 2008 the population of Italy was about 59,600,000.
Historians estimate around 30-60% population. But Numbers vary hugely.
France is more populated than Italy. France has a population of about 65,000,000 while Italy has a population of about 61,000,000.