After success in East Africa and a US release less than one year ago, Makumbi has disproved the naysayers and won one of the most lucrative literary prizes in the world, the Windham Campbell prize from Yale University
in the US.
Makumbi will take home $165,000 for her debut novel.
Makumbi told CNN that British publishers weren't particularly interested because it didn't include European aspects.
"Publishers in the UK are thinking about their readers in Britain and normally when they publish African novels they prefer to publish novels that deal with Europe as well," Makumbi said.
The book was first published in Kenya four years ago.
"The book was sold in East Africa and it was an instant hit," Makumbi said.
The Uganda author, now based in Manchester, moved to the UK at the age of 33, 17 years ago.
On receiving the award Makumbi said, "I couldn't believe it, I was crying. I'd just published one book and it's been out only less than a year in America."
Makumbi is one of eight writers to win a Windham Campbell Prize.
The book is about the myths of a Ugandan family who think they have been cursed since the 18th century.
"This novel had cut colonization out," Makumbi told CNN.
"It dates back to the 1700s before Europe arrived and the language itself is very Ugandan even though it's in English. There's quite a lot of Ugandan words. The story is told like it's spoken to Ugandans."
It's not the first award Makumbi has won. In 2014 she was awarded the Commonwealth Short Story Prize for her work "Let's Tell This Story Properly."
Makumbi's next book is a collection of short stories titled "Love Made in Manchester," to be released next January.
While publishers were slow to realize the novel's potential, Makumbi is positive about a growing audience.
"I think readers are more adventurous," Makumbi said.