With the end of the three-month intensive training in the foothills of Mount Behistun, Aban, the sharp-eyed and naturally gifted merchant, was ready to begin his mission in the heart of the commercial network of Persia and Media. Awestruck by little Kourosh's extraordinary intelligence and unparalleled insight, he had now not only learned the modern principles of trade and risk management but also possessed a treasure of secret knowledge: "Persian Numbers." During these three months, Kourosh had taught Aban the basics of Arabic numerals and the four main mathematical operations (addition, subtraction, multiplication, division). Since these Arabic numerals were unknown in that era, Kourosh had named them "Persian Numbers," and together, they had authored a book titled "An Introduction to Persian Numbers." This book was a revolutionary step in the science of mathematics, but for now, it was not to be published until the right time came.
Aban's mission was far more than a simple business venture. Under the guise of a young and ambitious merchant, he was to establish a commercial network in Anshan and the important cities of Media that would both serve as a cover for clandestine activities and provide the necessary financial resources for Kourosh's ideals. Using his innate business acumen and the new knowledge he had learned from Kourosh, he was quickly able to establish a foothold in the market. Aban introduced new goods from distant regions and, by using more efficient methods of buying and selling, demonstrated his ability to make greater profits. He even used the paper and the new New Persian script that Kourosh had invented to record transactions more accurately and to send trade letters to his partners; this, in addition to speed and accuracy, unwittingly helped to promote the new language and script and gave his business a progressive image.
Throughout his activities, Aban carefully looked for talented and trustworthy individuals to expand his network. He recruited young and intelligent merchants who were tired of the traditional accounting systems and were looking for ways to increase efficiency. Aban secretly taught them parts of "An Introduction to Persian Numbers," especially the four main operations that made complex calculations surprisingly simple. This knowledge was a blessing for merchants who dealt with a high volume of transactions. They quickly understood how these "Persian Numbers" and new methods could multiply the accuracy and speed of their work and bring greater profitability.
The use of "Persian Numbers" and modern accounting methods gave Aban an unparalleled competitive advantage. He could calculate prices with greater precision, quickly estimate the profit and loss of transactions, and make smarter business decisions. This efficiency earned the trust of other merchants, and gradually, his network expanded in the important cities of Media, like Ecbatana, and in the Persian regions. This network, in addition to its economic benefits, allowed Aban to secretly gather valuable intelligence on the pulse of different markets and the economic situation of the regions.
Of course, Aban's activities were not without challenges. Competition with traditional merchants who were accustomed to the old ways and sometimes looked at innovations with skepticism created difficulties. Also, the danger of theft or extortion on the trade routes always existed. But Aban acted with complete caution and, by building strong relationships with local tribes and using secret security measures, protected his caravans and goods. He also managed the profits cleverly so as not to attract attention and to prevent the main purpose of his clandestine activities from being revealed.
Ultimately, Aban secretly directed a portion of the large profits from his commercial activities towards Kourosh's hidden core. These financial resources were vital for Kourosh, as he could use them to finance the expenses of his intelligence networks, invest in future projects, and even equip his secret military forces. Kourosh, upon receiving regular reports from Aban and observing the significant growth of his commercial and financial network, was greatly pleased. He knew that this "Arm of Trade" was just as vital for building his thousand-year empire as the "Eye of Espionage" and the "Hidden Sword" that Arash and Fariborz were developing.
The book "An Introduction to Persian Numbers" and the knowledge contained within it remained a great secret in the possession of Kourosh and Aban for the time being. They knew that publishing this knowledge at this stage could create a great revolution in the existing sciences, but at the same time, it would also draw unwanted attention to them. Therefore, this intellectual treasure remained hidden, for now, awaiting the right time to be unveiled and to transform the ancient world.