By Oliver Woods BBC World Service business reporter in Vietnam

Vietnam's recent history has been turbulent, characterised by wars and political change.

The past 50 years have seen many Vietnamese leave the country to begin new lives in America, Australia and Europe.

But some of the descendents of this diaspora have now returned to Vietnam and have brought fresh business ideas with them.

Although they have had a mixed welcome.

Dramatic return

Two hours drive from Ho Chi Minh City is Long Hai, the former summer home of the last Vietnamese emperor.

It is now a holiday village owned by Anoa Dussol Perran, a French Vietnamese who left the country in 1961 with the departing colonial power.

Coffee was something that I wanted to improve in Vietnam and so I came back to start a coffee business

David Thai, coffee house owner

Thirty years later, she made a dramatic return.

Piloting her own helicopter she flew from Paris, over 22 countries, before landing in the Vietnamese capital Hanoi.

The authorities seemed less than impressed.

They were also suspicious about to her plans to start a helicopter piloting business.

Ms Perran said she came back to Vietnam with her own helicopters because she is a trained pilot and she thought she could use this skill to help her home country.

Coffee opportunities

Coffee house owner David Thai is opening a flagship cafe in Ho Chi Minh City.

He is a Vietnamese American from Seattle, but has been in Vietnam for eight years.

In the past two years we've seen a remarkable change in attitude on the part of the Vietnamese government

Tran Si Choung, James Riedel Associates

He first came back as a student, but soon realised there were business opportunities and he could utilise his experiences in America to exploit them.

"What you know and what you've been exposed to, you can bring that back to Vietnam," he said.

"I saw some business opportunities for example in coffee.

"Coffee was something that I wanted to improve in Vietnam and so I came back to start a coffee business."

Changing attitudes

After initial suspicions returning Vietnamese - or Viet Kieu - are now being accepted by many in the country.

They bring money, outside ideas and an understanding of the Vietnamese way of doing things.

Factors increasingly recognised by the Vietnamese government.

Tran Si Choung of US investment consultants James Riedel Associates said there were many untapped opportunities.

"In the past two years we've seen a remarkable change in attitude on the part of the Vietnamese government about the need to assimilate the towns, the resources, of the overseas Vietnamese," he said.

"But I still feel that we haven't even scratched the surface."

Changing Vietnam

Yet for many Viet Kieu it has been a struggle.

Anoa Dussol Perran ended her helicopter business and now runs a successful beach resort.

She said you have to have patience and need to understand the mentality of Vietnam to succeed.

Returning Vietnamese may not have the financial power of multinational corporations but they do offer something different - cultural understanding and enthusiasm that are already changing Vietnam.