How Zero Traveled from Kashmir to Rome

Many of us know that the number zero originated from India. But very few know the centuries-long journey it took before it became everyday math for the rest of the world. Reading William Dalrymple's The Golden Road ignited my curiosity, sending me down yet another rabbit hole of historical research. If you're a fan of history and mathematics, you'll find it amusing as well.

First question: who discovered zero? A simple Google search will reveal that it was the Indian Astronomer Brahmagupta (598-668 CE). This was a revelation to me. Had someone asked me this question, my answer would've been: Aryabhatta. While Aryabhatta did lay the groundwork for the development of zero, he used a placeholder in positional notation.

The discovery of zero can be a confusing topic to research. After all, ancient Babylonian and Mayans too used placeholders, which many argue were precursors to zero. Regardless of who came up with the concept, it was Brahmagupta that formalized the mathematical concept and published it in his book Brahmasphutasiddhanta when he was thirty.

But our inquiry isn't about who discovered it, but how this so called "nothing" made its way to the Romans.

The story begins in one of the most unexpected places: the serene valleys of Kashmir. Kashmir was once a bustling center of Indian learning. This is where Brahmagupta developed the concept.

This idea soon embarked started moving westward. The first leg of this journey took place in the late 8th century, when the decimal system, along with algebra, trigonometry, and the algorithm, made its way from India to the intellectual hubs of Abbasid Baghdad.

The key figures in this transmission were the Barmakids, a family of viziers in Baghdad with a unique background. Originally Sanskrit-literate Buddhist priests from Afghanistan, they had converted to Islam and risen to prominent positions in the Abbasid court. Khalid ibn Barmak (or his grandfather), the patriarch of this influential family, had studied Indian mathematics in Kashmir, then one of the great centers of Indian learning.

Recognizing the value of Indian knowledge, Khalid's son sent envoys to India with two specific missions: to learn Indian medicine and to study Indian mathematics and astronomy at the renowned observatory in Ujjain (my birthplace!). These expeditions bore fruit, bringing Indian scholars back to Baghdad, where they began the monumental task of translating Sanskrit scientific classics into Arabic.

This translation established not just Indian methods of healing and celestial observation, but also introduced the concept of zero in the Muslim world.

From Baghdad, these ideas spread further westwards in places like Egypt. Scholars in centers of learning from Cairo to Cordoba (under Moorish control) eagerly absorbed and built upon this knowledge. The works of Persian mathematician Al-Khwarizmi, particularly his book "On the Calculation with Hindu Numerals" (c. 825 CE), played a crucial role in disseminating Indian mathematical concepts, including zero, throughout the Islamic world and beyond.

As the Islamic Golden Age flourished, these mathematical innovations found their way to the edges of the Muslim world, including North Africa. It was here, in the coastal city of Bejaïa (in modern-day Algeria) where it will eventually cross the Mediterranean.

Fast forward about half a millennium to 1202 CE. A young Italian mathematician named Leonardo of Pisa (born c. 1170 CE), better known by his nickname 'Fibonacci' (yes, the same guy that came up with the famous sequence), returns from Algeria to his homeland. Fibonacci had grown up in a Pisan trading post in Bejaïa, where he had immersed himself in Arab culture and mathematics, becoming fluent in Arabic and well-versed in the mathematical innovations that had originated in India centuries earlier.

At the age of thirty-two, Fibonacci penned his magnum opus, the "Liber Abaci" (Book of Calculation). This seminal work introduced Europe to the Hindu-Arabic numeral system, including the concept of zero. Fibonacci's book was a revelation to European mathematicians and merchants alike, offering a more efficient system of calculation that would soon revolutionize (literally and figuratively) commerce and science across the continent.

The impact of the "Liber Abaci" cannot be overstated. It seeded a commercial revolution that would help finance the [[Renaissance]], as the new numerical system made complex calculations easier and more accurate. As these ideas spread northward, they contributed significantly to the economic rise of Europe.

And so, the concept of zero, born in the scholarly traditions of ancient India, nurtured in the intellectual crucible of Baghdad, and refined in the bustling markets of North Africa, finally found its way to the heart of Europe. From Kashmir to Rome, zero's journey spanned continents, cultures, and centuries, leaving an indelible mark on human knowledge and progress.

The journey of zero was neither straight nor inevitable. It depended on translators in Baghdad, merchants in North Africa, and a curious Italian mathematician. What we take as universal knowledge today was once fragile, contingent, and easy to lose. It is truly amazing how ideas, much like people, can travel across vast distances, transcend cultural boundaries, and mold the world in ways their originators could scarcely have imagined.