>Are there good historical examples of this happening, where foundational knowledge is completely lost? Usually following the fall of empires. Ibn Khaldun (133

>Are there good historical examples of this happening, where foundational knowledge is completely lost? Usually following the fall of empires. Ibn Khaldun (1332-1406) wrote: "Perhaps they have written exhaustively on this topic, and their work did not reach us. There are many sciences. There have been numerous sages among the nations of mankind. The knowledge that has not come down to us is larger than the knowledge that has. Where are the sciences of the Persians that ‘Umar ordered to be wiped out at the time of the conquest? Where are the sciences of the Chaladaeans, the Syrians and the Babylonians, and the scholarly products and results that were theirs? Where are the sciences of the Copts, their predecessors? The sciences of only one nation, the Greeks, have come down to us, because they were translated through Al-Ma’mun’s efforts. He was successful in this direction because he had many translators at his disposal and spent much money in this connection."