We stayed in Tehran, a car congested and noisy city just long enough to visit the Golestan Palace and the crown jewels collection before flying to Kerman, our southernmost destination, to begin our drive back north. From Kerman, our coach took us westward to Shiraz, then northeast to Yazd and west again to Isfahan, then due north to Tehran again. The last leg was northwestward to Zanjan and Tabriz before returning east and south back to Tehran by way of the coast of Caspian Sea. Each leg was 200-300 miles apart. Our zigzag tour left out the northeastern part of the country but covered the heartland of Iran's historical and cultural heritage.

Tapping qanat tech

As we drove through central Iran and saw endless stretches of arid desert country surrounded by treeless mountains, it dawned on me that qanat was likely the most important engineering invention that the ancient Persians contributed to the world. Aside from being a handy word for the Scrabble player to know, qanat is an irrigation system that can draw water from snow-capped mountains down to towns and villages miles away. The channel has to be carefully sized and gently graded so the water flow will remain smooth (what engineers called 'laminar flow') and not surge or become turbulent and the channel has to be kept underground to minimize evaporation and contamination en route to the final destination. Regularly spaced vertical shafts from the surface allowed for maintenance of the qanats.

The 19th century Shahzadeh Garden in Mahan, where we had lunch on our first outing out of Kerman, was an excellent example of how a qanat can create a beautiful oasis in the middle of the desert. Gushing water cascaded down terraces feeding the flowers and trees that lined both sides of the fountains. The water then exited the garden at the bottom of the hillside and went on to serve the people in Mahan. We were to see other working qanats on other segments of our tour. The qanats reminded me of the karezes in Turfan that we saw while on a tour of China's Silk Road — same idea with a different name that most likely originated from ancient Persia.

The Persian qanat is arguably even more significant to the development of the human civilization than the Roman aqueduct. Without the ingenuity of qanats, the arid and desiccated land of central Asia would remain sparsely inhabited to uninhabited, and could not become cradles of kingdoms and civilizations. The idea of the qanat spread from Persia to Syria, Egypt and Morocco in one direction and to Afghanistan and China in the other. The UN finds relevance in today's working qanats as case studies to help solve the world's challenges with polluted water.

By the time our coach pulled into Isfahan and drove along the river that bisected the city into northern and southern halves, the parks that lined both shores prompted me to modify my impression of Iran as one endless arid landscape. Tabriz to the northwest was even greener. From Tabriz as we emerged from a long tunnel on the way to Ardabil, we were surrounded by lush forest and were greeted by fog and rain. The countryside along the coast of the Caspian Sea was checkerboards of rice paddies as if we were in China. Because our tour included Tabriz and the Caspian shore, we formed a more complete impression of Iran than those that only saw Shiraz, Yazd, Isfahan and Tehran.

China and Iran

From the sampling of exhibits from museums we visited, I got the impression that the Neolithic people in Iran were capable of producing sophisticated forms of pottery to my amateur eye, every bit as advanced as those from China and perhaps even more advanced. Later, Persians got to be quite skilled working with stone as can be seen at Persepolis. By the same period as Persepolis, China had already developed the technology for intricate bronze casting that seemed to be missing in the Persian culture.

A Neolithic drinking vessel