Egypt's succeeding dynasty failed to reassert full control over Kush. Around 590 BC, however, an Egyptian army sacked Napata, compelling the Kushite court to move to a more secure location further south at Meroë near the Sixth Cataract. For several centuries thereafter, the Meroitic kingdom developed independently of Egyptian influence and domination, which passed successively under Iranian, Greek, and, finally, Roman domination. During the height of its power in the second and third centuries BC, Meroë extended over a region from the Third Cataract in the north to Soba, near present-day Khartoum, in the south. An Egyptian-influenced pharaonic tradition persisted among a line of rulers at Meroë, who raised stelae to record the achievements of their reigns and erected Nubian pyramids to contain their tombs. These objects and the ruins of palaces, temples, and baths at Meroë attest to a centralized political system that employed artisans' skills and commanded the labour of a large work force. A well-managed irrigation system allowed the area to support a higher population density than was possible during later periods. By the first century BC, the use of Egyptian hieroglyphs gave way to a Meroitic alphabet adapted for the Nubian-related language spoken by the region's people.