Answer:
The Italian city-states were a political phenomenon of small independent states mostly in the central and northern Italian Peninsula between the 9th and the 15th centuries.
After the fall of the Western Roman Empire, urban settlements in Italy generally enjoyed a greater continuity than in the rest of western Europe. Many of these towns were survivors of earlier Etruscan, Umbrian and Roman towns which had existed within the Roman Empire. The republican institutions of Rome had also survived. Some feudal lords existed with a servile labour force and huge tracts of land, but by the 11th century, many cities, including Venice, Milan, Florence, Genoa, Pisa, Lucca, Cremona, Siena, Città di Castello, Perugia, and many others, had become large trading metropoles, able to obtain independence from
The answer to this question is Longintudinal
Longintudinal research design is a tyoe of ressearch design that involved asking repetitive observations over same variables.
In a lot of cases, longintudinal research could take more than 10 years since the process is really long and repetitive.