Passage: Linguistic evidence shows that over time Nilotic speakers, such as the Dinka, Shilluk, and Luo, took over. These groups spread from the Sudd marshlands, where archaeological evidence shows that a culture based on transhumant cattle raising had been present since 3000 BCE, and the Nilotic culture in that area may thus be continuous to that date. Archaeological evidence, as well as the physical evidence in the livelihood of the Nilotes including their dome-shaped houses and tukuls, shows that they may have made an enormous contribution to the governance and wealth of the Nubia Kingdom before and during the 25th Dynasty.The Nilotic expansion from the Sudd Marshes into the rest of South Sudan seems to have begun in the 14th century. This coincides with the collapse of the Christian Nubian kingdoms of Makuria and Alodia and the penetration of Arab traders into central Sudan. From the Arabs, the South Sudanese may have obtained new breeds of hump-less cattle. Archaeologist Roland Oliver notes that the period also shows an Iron Age beginning among the Nilotics. These factors may explain how the Nilotic speakers expanded to dominate the region.

Question: Which kingdoms met an unfortunate collapse?
the Christian Nubian kingdoms of Makuria and Alodia