Input: Article: Geology did not undergo systematic restructuring during the Scientific Revolution, but individual theorists made important contributions. Robert Hooke, for example, formulated a theory of earthquakes, and Nicholas Steno developed the theory of superposition and argued that fossils were the remains of once-living creatures. Beginning with Thomas Burnet's Sacred Theory of the Earth in 1681, natural philosophers began to explore the idea that the Earth had changed over time. Burnet and his contemporaries interpreted Earth's past in terms of events described in the Bible, but their work laid the intellectual foundations for secular interpretations of Earth history.

Now answer this question: What theory did Nicholas Steno discover?

Output: the theory of superposition

Input: Article: The kingdom is mentioned in the Periplus of the Erythraean Sea as an important market place for ivory, which was exported throughout the ancient world. Aksum was at the time ruled by Zoskales, who also governed the port of Adulis. The Aksumite rulers facilitated trade by minting their own Aksumite currency. The state also established its hegemony over the declining Kingdom of Kush and regularly entered the politics of the kingdoms on the Arabian peninsula, eventually extending its rule over the region with the conquest of the Himyarite Kingdom.

Now answer this question: Which kingdoms did Aksum regularly enter the politics of?

Output: on the Arabian peninsula

Input: Article: After defeating the Visigoths in only a few months, the Umayyad Caliphate started expanding rapidly in the peninsula. Beginning in 711, the land that is now Portugal became part of the vast Umayyad Caliphate's empire of Damascus, which stretched from the Indus river in the Indian sub-continent (now Pakistan) up to the South of France, until its collapse in 750. That year the west of the empire gained its independence under Abd-ar-Rahman I with the establishment of the Emirate of Córdoba. After almost two centuries, the Emirate became the Caliphate of Córdoba in 929, until its dissolution a century later in 1031 into no less than 23 small kingdoms, called Taifa kingdoms.

Now answer this question: How long did it take the Emirate to become the Caliphate of Codoba?

Output:
almost two centuries