7 km north of Bursa, a city which has been a stage of settlement for 5,000 years, and 2.5 km south of the Demirtaş region, we find the Demirtaş Tumulus, with a diameter of 90 metres and a height of 5 metres found here were pottery sherds of bowls, jars and jugs, all generally handmade, with a few made with use of a wheel. These pieces date back to the Early Bronze Age, ca. 2500B.C.
The dimensions of the "Çayırköy Tumulus", located 14 km west of the city and l km southwest of the village Çayırköyü, are identical to those of Demirtaş Tumulus. The dominant colours of the ceramic found here are grey, red, grey-brown and black. An important part of the ceramics found were handmade, although the wheel was used for some of the pieces. The oldest finds here dates back to 2700 B.C.
Unable to defend themselves against the Scythian invasions, the Bithynians and their relatives the Tnynians living on the shores of the river Strumon in Thrace migrated to northwestern Anatolia in the VIIth century BC and remained in this area settled by mankind for over 5,000 years. They named this fertile land Bithynia. Although the Bithynians extended their territories rapidly, they could not escape domination by the Lydians, who possessed a strong army. in 546 B.C. the Lydian ruler Croesus was defeated by the Persian armies, and the region fell under the rule of the Persian Empire until 453 B.C.
The domination of the region by Alexander Great lasted from 325 B.C. until the emperor's death. Following the death of Alexander, Bithynia and Asia Minor were distributed among the military commanders and fell under the administration of Antigonos. But the struggle between Alexander's commanders continued and the Bithynian Kingdom took advantage of this chance. The Bithynian ruler Doidalses developed an independent Kingdom in the region. Under the rule of Zipoites (327-279 B.C.), the Kingdom was recognized and respected by its neighbors. During the rule of Zipoites' son Nikomedes I (279-250 B.C.), the Kingdom was enlarged and became the most respected Kingdom of Asia Minor.
During the years 278-277 B.C., the Galats, advancing in three branches from Middle Europe, entered western Anatolia and invaded and pillaged every settlement they came across. Following these invasions, various city-states were formed in Anatolia. After this tremor, Ziaelas (192-146 B.C.), Nikomedes II (146-92 B.C.), Nikomedes III (92-75 B.C.) and Nikomedes IV (75-74 B.C.) ruled the country. Nikomedes II made treaties with the King of Pontus, Mithridates, against the Roman Empire in the west. But Nikomedes III, who succeeded his father, did the opposite, fo the Kingdom of Pontus. Although the outcome of the conflict was not in Nikomedes' favour, he was able to sustain his independence thanks to the support of the Roman Empire. Nikomedes IV, who succeeded him at his death, turned over his lands to the Roman Empire in 74 B.C.. Thus, the Bythinian Kingdom became a province of the Empire. Pliny, who was appointed during the reign of Emperor Domitian, was promoted to governor during the reign of Emperor Traianus. After seizing the sovereignty over the region, he commenced the re-building of the cities. Nevertheless, the cities of Nicaea (İznik) and Nikomedia (İzmit) profited more from these activities than Prusa, where only one bathhouse was rebuilt. Ancient sources name Prusias I (232-192 B.C.) as the founder of today's Bursa. The Carthaginian King Hannibal, upon losing his battle against the Roman Empire, took refuge at the court of Prusias I with his army. Here, he is met as a victorious commander and respected as such. in return, Hannibal and his soldiers built a city. He named the city Prusias and presented it to the king. The city, which was surrounded by a fort when it was founded, was not bigger than a single neighborhood today. Very important documents dating back to the 2nd century B.C. were found within a tumulus belonging to the Bythinian Kingdom era.
During the Roman Empire period, the city was called Uludağ's Bursa, Prusa ad Olympium, and a marble statue of a woman and an osteotheque belonging to the period was found. During the reign of Emperor Justinianus (527-565), new bathhouses were built in Pythia (Çekirge), in 1935, vaulted chambers were discovered in the fort. Within the fort, early Byzantine floor mosaics found in Yer Kapı are among the most important archaeologic remains. Between the years 1204 and 1261, Prusa (Bursa) continued its existence as an undistinguished city under the feudality of Nicaea (iznik). Today, the richest Byzantine gravestone stele and other architectural works of art, ceramics and coins are exhibited in the Bursa Archaeological Museum.