Treaty of Zadar in 1358, Ragusa achieved relative independence as a vassal-state of the Kingdom of Hungary.
Between the 14th century and 1808, Ragusa ruled itself as a free state, although it was a vassal from 1440 to 1804 of the Ottoman Empire and paid an annual tribute to its sultan. The Republic reached its peak in the 15th and 16th centuries, when its thalassocracy rivalled that of the Republic of Venice and other Italian maritime republics.
For centuries, the Republic of Ragusa was an ally of Ancona, the other Adriatic maritime republic rival of Venice, which was the Ottoman Empire's chief rival for control of the Adriatic. This alliance enabled the two towns set on opposite sides of the Adriatic to resist attempts by the Venetians to make the Adriatic a "Venetian Bay", also said to control directly or indirectly all the Adriatic ports. Ancona and Ragusa developed an alternative trade route to the Venetian (Venice-Germany-Austria): this route started from the East, passed through Ragusa and Ancona, then interested Florence and finally Flanders.
The Republic of Ragusa received its own Statutes as early as 1272, statutes which, among other things, codified Roman practice and local customs. The Statutes included prescriptions for town planning and the regulation of quarantine (for sanitary reasons).
The Republic was an early adopter of what are now regarded as modern laws and institutions: a medical service was introduced in 1301, with the first pharmacy, still operating to this day, being opened in 1317. An almshouse was opened in 1347, and the first quarantine hospital (Lazarete) was established in 1377. Slave trading was abolished in 1418, and an orphanage opened in 1432. A 20 km (12 mi) water supply system was constructed in 1436.
The city was ruled by the local aristocracy which was of Latin-Dalmatian extraction and formed two city councils. As usual for the time, they maintained a strict system of social classes. The
