11436
The main western system , extending into Libya and Sudan , consists of a multi-layered artesian basin where massive groundwater reserves accumulated , principally during pluvials of the Quaternary .
 Libya, Sudan
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 Libya, Sudan