By 400 b.C., Persian engineers had mastered the technique of storing ice in the middle of summer in the desert. The ice could be brought in during the winters from nearby mountains, but more commonly they had a wall made along an east-west direction close to the yakhchal. In winter, the qanat water was channelled to the north side of the wall. The shadow of the wall made the water freeze more quickly so more ice was produced per winter day. Ice was stored in a specially designed, passively cooled refrigerator. This was a large underground space (up to 5,000 m3) that had thick walls (at least two meters at the base) made out of a special mortar called sārooj, composed of sand, clay, egg whites, lime, goat hair, and ash in specific proportions, and which was resistant to heat transfer. This mixture was thought to be completely water impenetrable. The space often had access to a qanat, and often contained a system of windcatchers or wind towers that could easily bring temperatures inside the space down to frigid levels in summer days. The ice was then used to chill treats for royalty during hot summer days.
The Islamic Republic of Iran has been occupied since 4000BCE, making Iran home to the world's oldest continuous civilization.It is located in central Eurasia on two ancient trade routes. One runs North-South and connects the Caspian Sea to the Persian Gulf, the other one goes East-West between China, India, Europe and Africa.There's a city called Isfahan at the intersection of these two routes, which at one time was the wealthiest city in the world. Isfahan was twice the capital of the Persian Empire, during the Median and then Safavid Dynasties.Interesting artifacts from pre-Islamic Persia include the cylinder of Cyrus the Great, which is the world's first written declaration of human rights. The hanging gardens of Babylon (one of the seven wonders of the ancient world) and the Code of Hammurabi (a set of rules which outlast the King) are also on the list.The Persian Empire was so magnificent that returning Crusaders carried tales of its splendor and helped spark the Renaissance in Europe! Influence of the Zoroastrian teachings of equality also inspired Greek philosophers such as Aristotle and Socrates.The Persian Empire was conquered by Muslim Arabs around 650CE during the Sassanid Dynasty. Initially the Zoroastrian, Christian and Jewish faiths were tolerated but by 1000CE most Persians had accepted Islam.In the sixteenth century Shi'a Islam was declared in Isfahan to be the national religion of Persia and the second golden age began. From 1500 to 1720 the Safavid Dynasty built the greatest Iranian empire since before the Islamic conquest of Persia.Because of its strategic location and oil resources, World War I found Persia in the middle of conflicts between the Ottoman Empire, Russia and the British Empire-via-India. Persia became Iran as of 1935 and was ruled by the Shah, a Persian term for "monarch."In the Islamic Revolution of 1979 Iran re-established a theocratic government under the Ayatollah Khomeini.Today the capital of Iran is the city of Tehran, and Iran is known as the world's center of Shi'a Islam.Text by Steve Smith.