<prompt> Translate the following text to EnglishMaelezo ya kwanza ya makazi haya ya kawaida katika eneo la juu la Castile, lililolindwa na safu ya milima ya Guadarrama, yanaonekana katika karne ya tisa.  <response>: The first solid references to this obscure settlement on the Castilian plateau, guarded by the looming Guadarrama mountain range, appear in the 9th century. 