Official Persian government dispatches dealing with national interests were entrusted to a State postal service. The Bible book of Esther describes how the Persian system worked: “[Mordecai] proceeded to write in the name of King Ahasuerus and do the sealing with the king’s signet ring and send written documents by the hand of the couriers on horses, riding post horses used in the royal service, sons of speedy mares.” (Esther 8:10) The Roman Empire had a similar service for administrative and military dispatches.

Private mail, such as letters written by the apostle Paul or others, did not qualify to be carried by such means. If one was wealthy, he could dispatch a slave to deliver a letter. Most, however, would have letters conveyed by acquaintances, or even strangers, who were traveling in the right direction. Family, friends, soldiers, or merchants were all potential postmen. An important concern, of course, would be how trustworthy the letter carrier was and whether he would convey the message carefully and intact. The Bible suggests that Paul entrusted at least some of his letters to fellow Christians who were traveling.​—Ephesians 6:21, 22; Colossians 4:7.

The nation’s economy was mainly based on farming, herding, and bartering. The Bible mentions markets at city gates​—“the Sheep Gate,” “the Fish Gate,” and “the Gate of the Potsherds.” (Nehemiah 3:1, 3; Jeremiah 19:2) These names appear to refer to the merchandise sold in each location. The Scriptures also mention Jerusalem’s “street of the bakers,” as well as a number of trade goods.​—Jeremiah 37:21.

What about prices? One Bible commentary states: “Prices naturally fluctuated through the centuries, and it is difficult to ascertain how much a particular commodity may have cost at a given time and place.” Still, information from ancient sources, including the Bible, shows that even back then, prices were subject to inflation. For example, slaves were commonly traded in antiquity. Joseph was sold for 20 silver pieces, which may have been shekels, probably the average price for a slave during the 18th century B.C.E. (Genesis 37:28) Three hundred years later, the price was 30 shekels. (Exodus 21:32) By the eighth century B.C.E., the price was 50 shekels. (2 Kings 15:20) Two centuries later, during the Persian period, prices went as high as 90 shekels or more. Apparently, rising prices are not just a plague of modern-day life.