In 2009 visiting at Benue State University in Makurdi, Nigeria, I found in the university bookshop Famine in Heaven by Odo Stephen.

Two sisters, one Christian, one Muslim, lead the world into a feminist utopia. They travel in spacecraft to Venus, the Moon, and eventually heaven—but much of the book takes the form of philosophical debates.

The book was so unusual, so different from anything I'd read (except, oddly, some of the science fiction by Mark Twain), that I tried to find more African SFF. Looking at the spread of mobile telephones and cybercafés in Nigeria, I knew there had to be some.

I didn't know it at the time, but already, in 2008, Chimurenga magazine in South Africa had published a special issue of science fiction by Africans, Dr. Satan's Echo Chamber.

Going online in 2009 I found that someone was trying to get writers and architects to collaborate on a science fiction anthology. The collective was called Lagos 2060.

In the eight years since 2008, there has been an explosion of African fantasy and science fiction. AfroSF, the anthology edited by Ivor Hartmann, was published in 2013, beating Lagos 2060 to be the first book anthology in the current wave.

The explosion is partly explained by the rapid growth of the web and of smartphones. It is easier to publish and distribute online rather than by print and road, especially in Africa. Omenana is a dependable, regular publication devoted to SFF. Brittle Paper publishes an impressive range of African writing, some of it speculative.

The development of Africa's publishing industry from Kwani? in East Africa to companies like Kachifo Limited and Cassava Republic Press in West Africa began to provide Africa with its own, beautifully published books.

But that is only part of the story.

This is the hypothesis for now: conditions for African writers now resemble the conditions in the early twentieth century that led to the USA taking over from Europe as the centre of science fiction and fantasy.

One of those conditions is diaspora.

Around the turn of the twentieth century, the USA had two great diasporas at once.

From 1900 to 1920, one third of Americans left farms and moved to cities—often not the old established cities of the East Coast. This migration included a huge movement by African Americans out of rural poverty in the South. Black or white, people escaped rural life often by moving up the Mississippi River towards Chicago. Chicago drained the Midwest of geeks, misfits, bored farmers, musicians, actors, bootleggers, fantasists, religious lunatics, quacks, inventors, and ambitious people of all types.

It was in Chicago that L. Frank Baum wrote The Wonderful Wizard of Oz, published in 1900. It was where Frank Lloyd Wright invented much of how the future would look (and who had his office in the same building as Baum). Edgar Rice Burroughs was a pencil salesman in Oak Park, Chicago when he wrote and sold his first story, "A Princess of Mars," in 1912. It was in Chicago that the skyscraper and the elevated railway, urban blues, and northern jazz were developed—not New York.

The other great diaspora, at the same time, was the second wave of migrants from Europe. From 1892 to 1952, 12 million immigrants from Europe arrived through one immigration centre: Ellis Island near New York. The peak year of European immigration was in 1907, when 1,285,349 persons entered the country. By 1910, 13.5 million immigrants from Europe were living in the United States. Laws against immigration by Chinese or black people limited numbers from other continents.

These migrants, mostly from Southern and Eastern Europe, found themselves in a country that could be hostile. They faced linguistic challenge, religious bigotry, cultural difference, and economic hardship. They did menial jobs to pay for their children's education. Some of the children of this diaspora would number among the greatest contributors to American fantasy, from Superman to the Laws of Robotics.

Diasporas are a geographical break, certainly. But their main power is that they are also a break from a past, specifically a past culture.

America's move to the big city meant two different cultural breaks. The first was with frontier values, the culture of the independent homestead where you made your own shoes—rather like Dorothy leaving the lonely Kansas farm and tripping to the Emerald City. The second break was with small-town values, the decency enforced by constant surveillance—like Superman leaving Smallville (also, in the current continuity, in Kansas). Metropolis is most often identified as being Chicago.

Cities offered anonymity, freedom, opportunity and, curiously, a new kind of interdependence. You were alone but in a crowd. You could work in a range of specialist jobs, get any kind of service or entertainment you wanted, and have sex with a new range of people.

The European diaspora meant that second-generation immigrants were, like Clark Kent, passing as mainstream Americans while nursing another identity based on a faraway kingdom, a lost past.

Science fiction and fantasy are rooted in a habit of mind that loves to see dreams made flesh and reality re-imagined. One reaches out to the future, the other looks towards a past, but I would say both come from a similar impulse. F and SF walk hand in hand.

A break with old culture opens up new possibilities in the present and for the future. Diasporans often dream of a better personal future, and it's a short step to dream of other futures for everyone else. The loss of culture draws the gaze backwards in time, to other values.

Diasporas make you the Other. You know better what it is like to be an alien.

Your language, your dress, your food, and your religion—everything about you is strange, at least to these Others who now have power. Perhaps you begin to see yourself though their eyes, develop a cultural double vision. You modify, perhaps, how you dress, speak, write, or wear your hair. You might change how you spell your name, or call yourself a name they can pronounce. You see the old country in a new light. Or you value all over again the things you have lost and have had to move away from, be they church socials in Smallville or orthodox religion in Minsk.

You know that change is possible: real change, changes that make you wonder what it is to be human.

So you begin to write traditional belief fiction, stories based on fairy tales from the old country. You rewrite Alice in Wonderland for American audiences. You begin to write stories of the future when you are better off, or the world has progressed.

I don't think I need to belabour parallels with possible experiences of Africans in diaspora.

By diaspora I mean different things. I mean Africans who have moved permanently to the West and their children who were born there. I also mean those now temporarily in the UK for an education, or to make some money. I do mean those who had to leave for their own safety, as well.

One thing I have noticed. The work of Africans who are now in the UK or in the West is of immense relevance to Africa, dealing with African themes. Richard Oduor Oduku, who we spoke to in Part One, talks about how much Jennifer Nansubuga Makumbi's Kintu means to him. Tade Thompson in this chapter tries to account for why so many topflight African women writers are, to some degree, diasporan.

There is a sense that diasporan writers speak for all Africans. And this is because, I think, all Africans are in diaspora—in this sense:

If diaspora means a cultural break, then all Africans at home or abroad have gone through a situation in which their country has moved from them, not them from it.

In Part One, Kiprop Kimutai talked about how it has only been three generations since his family were living a traditional life, and speaking their own mother tongue.

Colonialism, and then internalized colonialism, both have wrenched African cultures away from home without the people having to physically move. Globalization, new technology, new media continue to do the same. This is a different kind of scattering, but a scattering all the same.

Tendai Huchu, in the last line of the last interview of this section, says, "… there is nothing special here." The surprise for many Africans coming to the West is that there is no surprise.

Africans for generations have been educated in Western languages and on Western models. Ordinary African homes have widescreen TVs, DVD players, and fridge freezers. The internet and smartphones mean that their children have access to YouTube, iTunes, social media, and e-books. In terms of youth culture, at least, there is not that much of a difference between life in or out of the diaspora.

And that internal cultural diaspora, that break with past, may well explain why so many Africans now are turning towards traditional beliefs and stories, or looking ahead with excitement to the future, and why there is such a cultural continuity between writers in and out of Africa.

In other words, this other scattering of culture helps explain the rise of SFF and speculative fiction inside Africa as well.

For Chikodili Emelumadu, coming back to Britain was such a disappointment that she returned to her Igbo cultural inheritance.

For others such as Joy Gharoro-Akpojotor the West means increased opportunity to question gender and sex roles. But as we have seen in Part One of this series, this is happening as well within Africa, despite opposition.

First, we meet Ayodele Arigbabu, one of the founding fathers of African science fiction: literally an architect of the future.

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