The Eurasian Crossroads: Two Rising Powers

The 7th century marked a pivotal moment in Eurasian history with two simultaneous developments that would reshape the continent: the meteoric rise of Islamic caliphates and the reunification of China under the Tang Dynasty. Within a remarkably short span, Islam emerged as the dominant faith across a vast arc stretching from Portugal to the Indus Valley, while Tang armies pushed westward across 2,000 miles of deserts and steppes. These expanding civilizations would eventually meet along the frontiers of Central Asia, creating both conflict and opportunity.

As these empires underwent internal transformations, merchants began shifting their focus from the overland Silk Roads to maritime routes. The Indian Ocean trade network, connecting Southeast Asia to Northeast Asia, had existed for centuries but now flourished as sailors gained experience and confidence. Port cities like Srivijaya and the Chola kingdom grew wealthy from this commerce, using their profits to build powerful states that in turn attracted more traders – creating a virtuous cycle of prosperity and stability.

The Lightning Expansion of Islam

The early 7th century Arabian Peninsula was divided between the Byzantine and Sassanian empires, with only coastal regions under their control. This changed dramatically with the rise of Islam. By 634, Arab forces captured Damascus, which would serve as the caliphal capital for over a century. After conquering Alexandria and Persia, the Umayyad Caliphate (established 661 CE) dominated Arabia, Mesopotamia and eastern Anatolia, pushing armies to the Caucasus Mountains.

Under governor al-Hajjaj ibn Yusuf (694-714), Islamic forces advanced into Afghanistan and Transoxiana (modern Uzbekistan), where many Persians and Turks converted from Zoroastrianism, Buddhism and Christianity. This strategically vital region served as the crossroads for Silk Road routes from Kashgar, the Taklamakan Desert, Afghanistan and India. Though Abbasid forces defeated the Tang army at Talas (751), Tibetan expansion northward checked further Islamic advances east.

Maritime Muslims: The Indian Ocean Transformation

Arab forces reached the Persian Gulf by 635, establishing Basra as a military camp. Within decades, Persian and Omani sailors converted to Islam and plied newly prosperous trade routes. While territorial expansion slowed, commercial growth continued – though it also led to increased piracy between the Indus Delta and Gujarat. To restore order, al-Hajjaj ordered expeditions into the Indian subcontinent in 711, the same year Tariq ibn Ziyad crossed into Iberia.

The conquest of Sindh under Muhammad ibn al-Qasim (712) saw many Buddhists convert to Islam and restored trade routes from India’s Konkan and Malabar coasts to Sri Lanka. However, this marked the eastern limit of Arab expansion in South Asia for three centuries.

The Abbasid Revolution and Baghdad’s Rise

Despite Islam’s rapid spread, the Umayyad caliphs in Damascus faced pressures from traditionalists and tensions between Arab Muslims and converts. Persian-Arab conflicts proved particularly acute. When Abu al-Abbas al-Saffah rebelled against Umayyad rule in 749 with Persian support, he established the Abbasid Caliphate and moved the capital 750 km east to Baghdad (founded 762).

This geographic shift redirected Islamic attention from the Mediterranean to Central Asia and the Indian Ocean. As 9th century geographer al-Yaqubi recorded, Caliph al-Mansur predicted Baghdad would become “the shore of the world,” accessible to ships from Wasit, Basra, Ahwaz, Fars, Oman, Yemen, Bahrain and beyond. Within fifty years, Baghdad grew to 500,000 inhabitants – rivaled only by Chang’an as the world’s largest city.

Competing Ports of the Persian Gulf

While ports like Ubulla, Basra and Siraf had declined in late Sassanian times, they remained vital to long-distance trade during the transition to Islamic rule. Basra quickly eclipsed Ubulla, growing to over 200,000 diverse residents by the 8th-9th centuries as a center of manufacturing, agriculture (especially dates), and culture.

Siraf, founded by Shapur II in the 4th century, became Baghdad’s main competitor. Despite harsh conditions, its deep-water anchorage attracted merchants trading with China and importing teak from India and East Africa. 10th century geographer al-Istakhri noted Siraf’s multi-story teak houses “overlooking the sea” rivaled Shiraz in splendor.

The Zanj Rebellion and Gulf Decline

The Abbasid golden age lasted nearly a century before challenges emerged. The massive Zanj Rebellion (869-883), supported by Gulf merchants resentful of caliphal interference, resulted in over 500,000 deaths and the sack of Basra in 871. While the caliphate nominally retained control, ports like Siraf and Sohar operated with increasing autonomy.

By the 10th century, Abbasid caliphs became figureheads as the Shiite Buyids took power. When a 976 earthquake devastated Siraf, it signaled the Gulf’s commercial decline. The Seljuk Turks’ 1062 capture of Shiraz and subsequent disinterest in maritime trade accelerated this trend, as merchants increasingly favored the resurgent Red Sea route under Fatimid rule.

Red Sea Resurgence

Initially, Muslim control of Egypt brought little Red Sea traffic beyond pilgrimages and grain trade. However, by the 9th century, Persian sailors frequenting Jeddah and Aden traded goods from Sindh, China, Zanzibar, Abyssinia, Fars, Basra and Qulzum (Suez). Designated as Mecca’s port in 646, Jeddah became Islam’s most important harbor despite its treacherous approach.

When Seljuks took Sinai in the 1060s, the Red Sea trade grew with Egypt’s recovery. Pilgrims traveled up the Nile to Aswan, then by caravan to Aidhab – a pattern lasting until the Mamluks restored overland routes in 1267-68.

East Africa’s Swahili Coast

As long as Baghdad dominated western Indian Ocean markets, the Red Sea remained secondary to Persian Gulf routes. By the 8th century, trade extended beyond the Horn of Africa, with Omani merchants replacing Aksumite traders. Establishing themselves first on Socotra, they later settled coastal islands off Kenya and Tanzania before moving to the mainland.

Between the 8th-11th centuries, cities like Mogadishu, Lamu, Pemba, Zanzibar, Kilwa and Sofala (the southern limit of Indian Ocean trade before Portuguese arrival) emerged. Contrary to earlier assumptions, Swahili culture blended foreign influences with local traditions rather than being overwhelmed by Arab culture. Excavations at Shanga (with 8th century Persian pottery) and Kilwa (with 9th century Chinese goods) reveal this synthesis.

East Africa exported gold, ebony, tortoiseshell, iron and ivory while importing Chinese ceramics and glass. The less-documented Indian Ocean slave trade may have transported 25 million Africans between 850-1000, though Islamic slavery differed significantly from Atlantic models in legal rights and social mobility.

The Eastern Trade Routes

By the early 8th century, Persian Gulf sailors were making 6,000-mile voyages to China. Chinese Buddhist pilgrims like Yijing (673) and Vajrabodhi (713) traveled on Persian ships, joining fleets of 30 vessels carrying hundreds of passengers and precious cargoes. Arab accounts describe Persian merchants regularly sailing to Sri Lanka, Southeast Asia and Guangzhou for silks.

The process involved transshipment at Siraf, where goods from Basra and Oman were loaded onto China-bound ships too large for the shallow Gulf. After stopping at Muscat for water, ships sailed a month to Quilon (paying 1,000 dirhams tax), then past India and Sri Lanka to Nicobar Islands, the Malay Peninsula, and through the Malacca Strait to Srivijaya or directly across the South China Sea.

India’s Political Reconfiguration

Arab expansion halted in Sindh partly due to India’s political reorganization. The 8th century saw powerful kingdoms emerge – some through territorial conquest like the Rashtrakutas (controlling India’s west coast) and Palas (influencing Southeast Asian Buddhism), others through maritime trade.

Along former Sassanian routes, Muslim merchants established diaspora communities, particularly on the Konkan coast between Cambay and Chaul (Samar). By the 10th century, Samar had over 10,000 Muslims – Indian converts and immigrants from Oman, Siraf, Basra and Baghdad. These “nauvittaka” (ship-wealthy) communities enjoyed considerable autonomy under local rulers.

Further south, the caste system limited intermarriage, creating mixed “Mappila” communities that persisted until Portuguese arrival. Similar to Kilwa’s foundation legends, Persian refugees reportedly established seven settlements along India’s west coast under local rulers’ protection.

The Chola Interlude

On the Coromandel Coast, the Hindu Chola kingdom played a pivotal 9th-11th century role in Indian Ocean trade comparable to Fatimid Egypt or Song China. Tamil merchants developed sophisticated commercial methods, training from age 10 to independence at 41. Temple-based banking systems funded guilds specializing in commodities like textiles, oil or horses.

While Hinduism’s growing ritual strictness reduced direct maritime participation, Tamil networks extended from China to the Red Sea. The Cholas’ imperial ambitions culminated in Rajendra I’s 1025 raid on Srivijaya and its dependencies – a 1,500-mile naval expedition capturing fourteen cities. Though temporarily disruptive, Srivijaya’s trade missions to China rebounded by 1028, outnumbering those from Java and South India combined.

Ships of the Indian Ocean

Evidence of medieval Indian shipbuilding remains scarce. The Belitung wreck (c. 826), likely built in the Persian Gulf using African mahogany and Indian teak, measured about 20-22m long with stitched-plank construction. Arab accounts describe Omani shipbuilders using coconut wood for entire vessels – from hulls to sails and rigging. Whale oil protected hulls, while lime-animal fat mixtures (“nura”) were used in Aden.

The 11th century Yuktikalpataru warned against iron fittings due to magnetic dangers, though iron remained an important trade commodity. A unique 11th-15th century ship found near Kochi featured nailed (not stitched) planks and bulkheads – possibly Chinese-influenced. Javanese ship depictions at Borobudur (9th century) show outriggers likely for defense rather than stability, with distinctive “layar tanja” sails.

Advances in Navigation

Navigational knowledge advanced significantly, with the earliest pilot handbooks appearing by 1010. Arab sources describe intricate lighthouse networks in the Persian Gulf – some 40 ells tall with tile roofs and glass lamps. Red Sea navigation remained cautious, with ships anchoring nightly to avoid reefs.

The 15th century navigator Ahmad ibn Majid codified centuries of accumulated knowledge, emphasizing celestial observation, coastal familiarity, and instrument use. This professionalization built on earlier works like the 12th century Persian “Rah Nama” (Book of Routes).

The First Globalization

From the 7th-11th centuries, Indian Ocean sailors integrated regional markets from East Africa to China, laying foundations for enduring trade networks. This “proto-globalization” saw regional changes create ripple effects across vast distances – whether the Abbasids’ rise, Tang-Song China’s unification, or Srivijaya’s commercial dominance. The resulting interdependence spurred agricultural, industrial and technological advances while spreading religions and cultures across the maritime world.