Educationalists and historians have been meeting across borders to attempt the seemingly impossible - a common history textbook for South East Asia.

Not only will they have to accommodate diverse countries and a tangle of overlapping disputes, they have to contend with countries wanting to revise their history books to reflect territorial claims.

This ambitious task is taking place within the Association of South East Asian Nations (Asean) group of countries - Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, Philippines, Singapore, Thailand and Vietnam.

Textbook experts from the region met in Bangkok in Thailand last year to look at the idea of a common history.

"There are still fundamental miscommunications, deeply-held prejudices and emotionally-charged perceptions which we have to overcome," a former Asean secretary-general, Dr Surin Pitsuwan, told the meeting, organised by Unesco.

"This is just the first step in what will be a very long and complex process," says Tim Curtis, chief of the culture unit of Unesco's Asia Pacific regional office.

"Revising history textbooks is a never-ending story. But that does not mean we should not start."

Thai history scholar Kasetsiri Charnvit was succinct: "Bad history, bad education, bad neighbour relations."

The move towards an Asean single market in 2015 provides an extra impetus. As countries come together as an economic group it will allow free movement, trade and educational exchanges.

"It's a good starting point. People are willing to come together to talk about it," said Ivy Maria Lim, a historian and assistant professor at Singapore's National Institute of Education and co-editor of Controversial History Education in Asian Contexts.

The idea of a common Asean history textbook emerged after the Preah Vihear temple dispute between Cambodia and Thailand. Both claimed sovereignty over temple land on their common border.

Fighting erupted in 2011 after troop build-ups on both sides when Cambodia applied for Unesco World Heritage status for the site in 2008, interpreted as a claim over the area.

Other historical disputes, some going back centuries, involve Thailand and Laos, Cambodia and Vietnam, Malaysia and Indonesia, among others.

Beyond the Asean countries, there are separate disputes between China and Japan in the East China Sea, and competing claims in the South China Sea which have escalated recently.

In January, Vietnam's Prime Minister Nguyen Tan Dung asked the Ministry of Education to include Vietnam's sovereignty over parts of the disputed Paracel Islands and Spratly Islands in the South China Sea in school textbooks.

Vietnam disputes sovereignty of the Paracels with China, while other Asean countries, Brunei, Malaysia and the Philippines claim parts of the Spratlys, as do China and Taiwan in a tangle of claims and counter claims.

In such a climate, textbook writing is fraught with risk and governments can be reluctant to yield any ground.

Governments wield "very strong control over what goes in textbooks, what is written in the curriculum, how they want it to be taught", said Dr Lim.

"In South East Asia, the need to foster patriotism is felt acutely," says Filomeno Aguilar, Professor of History at Ateneo de Manila University in the Philippines.

Governments assert their claims over disputed territory through the rewriting of history textbooks - at the same time as air-bushing versions that could lead to opposing claims.

"It infects histories with political bias and prevents coverage of topics not allowed by the state," Prof Aguilar notes.

The approach in many Asean countries, says Prof Aguilar, is to suppress difficult topics in history. Sometimes this is justified as wanting to avoid antagonising neighbours.

Not every South East Asian country is keen on a joint history. Some wanted to get around the thorny problem of reconciling conflicting narratives by promoting the idea of a regional Asean identity, rather than a common history.

But, says Prof Aguilar, such a regional economic grouping is not a "neat fit" for individual countries' histories.

Because of vast differences in culture, languages, religion as well as colonial experiences, there isn't a shared Asean history.

One of the few commonalities between many of the countries has been wartime Japanese rule.

It might not be a dimension they want to explore - and Japan has taken a tough line with its history textbooks.

Prof Tokushi Kasahara, a progressive Japanese historian who has worked for years on a joint history textbook with South Korean and Chinese academics, does not believe that Japan will co-operate with Asean on re-examining history.

"Frankly there is no desire or will to create a joint history textbook with other nations among Japanese historians and educationalists," said Prof Tokushi.

Yet he continues undaunted working on a common North East Asian history, History of the Three Countries of East Asia.

"The prospect of achieving a common historical understanding will surely be realised only when citizens living in East Asia learn the truth of the regions' history of wars of aggression and colonial rule, and then engage in repeated dialogue and debate over how best to overcome these legacies of the past," said Prof Tokushi.

There are few successful precedents.

Prof Tokushi and academics from China, Japan and South Korea have spent years thrashing out differences in a non-governmental history textbook commission, without support from politicians.

If there are too many differences to be reconciled for a joint textbook, the Asean group could still produce joint guidelines on the way history could be taught in Southeast Asia.

That's the view of Eckhardt Fuchs, deputy director of the Georg Eckert Institute for International Textbook Research in Germany, invited by Unesco to advise the Asean group.

At least this could give people a "perspective that goes beyond their own national narrative," said Dr Fuchs, after South Korean President Park Geun-Hye proposed a common textbook as a way to build peace and economic cooperation in North East Asia.

The president had referred to the German-French joint history textbook as a model, published in 2006.

"It shows us that communication and collaboration on a joint textbook is possible. Once you sit together and discuss problems, there is a way to resolve them," said Dr Fuchs.

But it requires strong political will.