The explanation had to begin at the foundation, and Batu knew it, so he started there.
"Normally, a merchant moving silver from Sarai to Urgench carries that silver on the road."
He explained. "The road has bandits, delays, and unpredictable weather. There is always the risk the silver arrives late, arrives short, or doesn't arrive at all."
He let the context sit before continuing. "What can travel safely is paper, easy to store and worthless to bandits. So the silver stays in Sarai and a document representing it travels instead."
Saran looked at him with attention. She had not encountered the concept before, her body leaning forward on the search for its meaning.
"Mahmud's office is responsible to issue the document."
