The Abhiraja myth notwithstanding, more recent research does indicate that many of the places mentioned in the royal records have indeed been inhabited continuously for at least 3500 years. The earliest evidence of civilisation thus far dates to 11,000 BC. Archaeological evidence shows that as early as the 2nd century BC the Pyu had built water-management systems along secondary streams in central and northern parts of the Irrawaddy basin and had founded one of Southeast Asia's earliest urban centres. By the early centuries AD, several walled cities and towns, including Tagaung, the birthplace of the first Burman kingdom according to the chronicles, had emerged. The architectural and artistic evidence indicates the Pyu realm's contact with Indian culture by the 4th century AD. The city-states boasted kings and palaces, moats and massive wooden gates, and always 12 gates for each of the signs of the zodiac, one of the many enduring patterns that would continue until the British occupation. Sri Ksetra emerged as the premier Pyu city-state in the 7th century AD. Although the size of the city-states and the scale of political organisation grew during the 7th to early 9th centuries, no sizeable kingdom had yet emerged by the 9th century.