Context: Mu'awiyah introduced postal service, Abd al-Malik extended it throughout his empire, and Walid made full use of it. The Umayyad Caliph Abd al-Malik developed a regular postal service. Umar bin Abdul-Aziz developed it further by building caravanserais at stages along the Khurasan highway. Relays of horses were used for the conveyance of dispatches between the caliph and his agents and officials posted in the provinces. The main highways were divided into stages of 12 miles (19 km) each and each stage had horses, donkeys or camels ready to carry the post. Primarily the service met the needs of Government officials, but travellers and their important dispatches were also benefitted by the system. The postal carriages were also used for the swift transport of troops. They were able to carry fifty to a hundred men at a time. Under Governor Yusuf bin Umar, the postal department of Iraq cost 4,000,000 dirhams a year.

Question: Who first brought a postal service into Umayyad lands?
Answer: Mu'awiyah

Question: Along what highway did Umar bin Abdul-Aziz build caravanserais?
Answer: Khurasan

Question: Along with horses and camels, what animals were used by the postal service?
Answer: donkeys

Question: In dirhams, what was the yearly cost of the Iraqi postal service when Yusuf bin Umar was governor?
Answer: 4,000,000

Question: In kilometers, how far apart was each stage of the Umayyad highways?
Answer: 19

Question: Who ended the postal service?
Answer: Unanswerable

Question: Who shrunk the reach of the postal service throughout his empire?
Answer: Unanswerable

Question: Who stopped the use of horses in the postal service?
Answer: Unanswerable

Question: What service primarily met the needs of private citizens? 
Answer: Unanswerable

Question: What did the postal department of Iraq cost per year under Abd al-Malik?
Answer: Unanswerable