When a commoner named Liu Bang became the first emperor of the Han Dynasty in 206 B.C., it was the start of a period of more than 400 years that was marked by advances in everything from record-keeping to agriculture to health care.

“There were major inventions and developments in science and technology,” Robin D.S. Yates, the James McGill Professor in the Department of History and Classical Studies at McGill University in Montreal, explains. “As with all inventions, some of these only came into their own in later, sometimes much later times.”

Here are a few of the biggest breakthroughs of the Han Dynasty.

The Invention of Paper

Inventions of the Han Dynasty: Paper
API/Gamma-Rapho/Getty Images
The production of paper.

The earliest scrap of paper still in existence, a crude material made mostly from hemp fiber found in a tomb in China in 1957, dates back to sometime between 140 and 87 B.C. But Cai Lun, a eunuch in the Han court in A.D. 105, is credited as the inventor of the first really high-quality writing paper, which he fashioned by crushing and combining tree bark, hemp, linen rags, and scraps from fishing nets and then treating the mixture with lye to break it down into finer fibers, according to Li Shi’s book The History of Science and Technology in the Qin and Han Dynasty.

“Administrative documents continued to be written on boards of wood and slips of bamboo for several centuries—they preserved better, perhaps,” Yates explains. But after the collapse of the dynasty, Cai Lun’s improved paper came into its own.

The Suspension Bridge

Inventions of the Han Dynasty: Suspension Bridge
Buyenlarge/Getty Images
An undated photograph of a Chinese built suspension bridge, with boats docked at a pier in foreground, in the Szechwan Province, China.

According to Robert Temple’s highly-regarded history of Chinese inventions, The Genius of China, the Han Dynasty saw the development of the suspension bridge, a flat roadway suspended from cables, which probably evolved from simple rope bridges developed to span small gorges. But by A.D. 90, Han engineers were building more sophisticated structures with wooden planks.

Deep Drilling

Han Dynasty salt miners in the First Century B.C. were the first to build derricks and use cast iron drill bits to dig holes as deep as 4,800 feet into the Earth in search of brine, which they would extract from below with tubes, according to Temple’s book. The technique they developed was the forerunner of modern oil and gas exploration.

The Wheelbarrow

Inventions of the Han Dynasty: Wheelbarrow
SSPL/Getty Images
A model of a Chinese wheelbarrow.  It can accommodate a much larger wheel, thus reducing the rolling resistance, and by having the wheel almost directly under the load it reduced the weight on the user's arms.

The wheelbarrow was developed in China perhaps as early as 100 B.C, according to this 1994 article by M.J.T. Lewis in the journal Technology and Culture.

The Seismograph

Inventions from the Han Dynasty: Seismoscope
SSPL/Getty Images
The Chinese astronomer, mathematician and seismologist, Zhang Heng (78-139 A.D.) described the earliest seismoscope known in about 132 A.D. Arriving shock waves displace a pendulum linked to a mechanism which opens the jaws of the dragon facing the direction of the earthquake. A ball falls from the dragon's teeth into the mouth of a toad below to record the event.

Zhang Heng, an early Chinese scientist, explored fields ranging from astronomy to clock-making. But he’s probably best known for creating the first device for detecting distant earthquakes, which he introduced to the Han court in A.D. 132 Its design was simple—an urn equipped with a pendulum.

When it picked up a vibration, it dropped a ball from the mouth of a metal dragon into a metal frog, creating a loud clang. The first time that happened, nobody in the court reportedly felt anything, but a few days later, a messenger from a village 400 miles away arrived to inform the emperor that an earthquake had occurred there.

The Blast Furnace

Right around the beginning of the Han Dynasty in the early 200s B.C., Chinese metallurgists built the first blast furnaces, which pumped a blast of air into a heated batch of iron ore to produce cast iron, according to Chinese technology historian Donald B. Wagner.

The Adjustable Wrench

According to Temple, the First Century B.C. Chinese used a tool somewhat similar to the one used by plumbers and tinkerers, in which a sliding caliper gauge allowed the pieces to be adjusted. (Modern wrenches have a worm screw, a different mechanism, but the function is the same.) Initially, the devices seem to have been used for measuring, rather than loosening and tightening lug nuts or pipes.

The Moldboard Plow

Inventions of the Han Dynasty: Plow, Kuan
Universal History Archive/Universal Images Group/Getty Images
12th century Chinese print of a farmer and ox plow.

According to Robert Greenburger’s book The Technology of Ancient China, the Chinese were using iron plows to till farm fields as far back as the 6th Century B.C. But a couple of hundred years later, some ingenious Han inventor came up with the kuan, also known as the moldboard plow. The tool had a central piece that ended in a sharp point, and wings to push the soil away and reduce the friction. The new plow helped the Chinese practice contour plowing, in which they followed the shapes of the hills, to reduce soil erosion.

The Stirrup

Inventions from the Han Dynasty: Stirrups
Cl2004lhy/Getty Images
An illustration of a man on a horse dating back 2,000 years during the Han Dynasty.

Ancient horsemen had to let their legs dangle as they rode, though the Romans rigged a hand-hold on saddles to help them stay on the horse when things got rough. A Han Dynasty inventor made things a lot easier by making cast iron or bronze devices that a rider could slip his foot into, according to Temple. It was such a revolutionary invention that it spread over the next several centuries across Asia to Europe, where it made it possible for medieval knights to ride their steeds in heavy armor without tumbling off.

The Rudder

The Chinese developed the device for steering a ship in the First Century A.D., according to Chinese technology historian Yongxiang Lu.

The rudder enabled ships to steer without using oars, making it a lot easier to navigate. According to Temple’s book. the invention took about millennium to reach the west, where it helped Christopher Columbus and other explorers navigate the ocean.

HISTORY Vault: 101 Inventions That Changed the World

Take a closer look at the inventions that have transformed our lives far beyond our homes (the steam engine), our planet (the telescope), and our wildest dreams (the Internet).