Four years later, he moved from France to the town of Hoi An.
Although Hoi An is Réhahn's base, he spends much of his time motorbiking across remote parts of the country and taking photos of landscapes and locals.
Réhahn strives to capture his subjects in their most "natural and random moments," so that viewers can imagine the story behind that person.
Keep scrolling to see the incredible photos from his most recent trip through northern Vietnam.
Réhahn spent a total of 11 days in Vietnam traveling by motorbike to various small towns that are home to some of Vietnam's minorities. Here's a map of the places he visited.
These two sisters are part of the H'mong minority, one of the largest minority groups in the country.
The Hmong generally live in the north of country at high altitudes. Different kinds of H'mong people dress differently — Black H'mongs wear traditional indigo blue clothing, and Flower H'mongs wear more colorful dress.
This H'mong child was home alone when Réhahn photographed her.
Here, four H'mong children eat lunch.
This girl belongs to the H'mong Hoa group.
While traveling between villages, Réhahn often stopped along the way to capture breathtaking views from the road, as well as locals he ran into. This was taken on route to B?o L?c.
Réhahn was hoping to photograph members of the Lô Lô minority group while in B?o L?c. This 17-year-old is part of the Lô Lô Hoa ethnic group.
He photographed this six-year-old Lo Lo girl in the village of C?c S?n.
Réhahn visited Vietnam during the rainy season, which made some of his motorbike trips between villages difficult. Here's a photograph he took of the Dong Van Valley, which is located in the Ha Giang province.
This is the lunar terrain, which sits between Dong Van and Meo Vac.
This girl is from the Dong Van Valley.
Réhahn said it's sometimes hard to find people who still dress in traditional clothing.
This woman comes from Meo Vac.
The Red Dao people are mainly found in Nam Toong, Supan, and Ban Lech.
Here's a member of the Red Dao group harvesting corn.
While on his way to the village of Minh Th??ng to photograph the Pa Thèn ethnic group, Réhahn ran into a teacher who was on her way to school. He asked if he could visit the classroom to take photos.
According to Réhahn, poverty is the main issue that prevents children in remote Vietnamese villages from attending school.
He says getting to school is another problem for the children.
Some have to walk for more than two hours, crossing streams, valleys, and hills.
After visiting the school, Réhahn stopped by the home of the Minh Th??ng village leader. The wife of the leader put on traditional Pa Thèn clothing for this photograph.
The landscapes Réhahn captured are just as stunning as the locals he photographed.
"Sometimes I drive along the road to find that Vietnam is so beautiful, and I think I have just discovered the best view," Réhahn said. "Yet as I drive farther, I find a better view. Maybe I will never find the best view, but I know this will give me more determination to search for more."
Girls still marry young in some regions of Vietnam.
Réhahn said during his trip he met a girl who was married at age 14 and had her first child at 16.
This 13-year-old girl is part of the Dao Mán minority.
The traditional clothing of the Phu La people is bright and colorful. Their income sources include farming and selling handmade crafts such as baskets.
The Phu La plant on terraced fields. This rice field is in Hoang Su Phi, which is in the northeastern part of the Ha Giang province.
This 78-year-old man lives by himself in the village of Díu Th??ng. He's part of the La Chi group and invited Réhahn to his house to smoke thuoc lao, a bamboo water pipe.
The Pu Péo minority group build their homes in forests, which provide ideal conditions for growing food. They use resources from nature to help build their homes.
Réhahn's photography captures the soul of his subjects. "There are more emotions in his photos than words could tell," his website says.