Seamer Ebadot Hossain took a career best 6-46 as the tourists dismissed New Zealand for 169 early on day five at Mount Maunganui and then knocked off the 40 runs for victory for the loss of two wickets.
It was Bangladesh’s first win in any format of the game in New Zealand and gave them a 1-0 lead in the two-match series.
“I can’t describe it, it’s unbelievable. I couldn’t sleep yesterday because of the pressure,” skipper Mominul told reporters.
“It was very important to win this Test match. Two years ago, we didn’t play that much Test cricket, so we were keen to improve.
“This could be a sign of our improvement in Test cricket. Everyone supported each other during this match. I have said in the past that playing well collectively is the key to our success.”
Bangladesh had gone into the match focusing on the process rather than the result, he added.
“You have to have a clear mindset before playing anywhere. If you’re going out of the subcontinent, and you think to yourself that ‘it will be tough,’ then it will be tough,” said Mominul.
“We didn’t focus too much on the result of the Test matches, we tried to focus on the process.”
The Bangladesh captain also praised the performance of Ebadot, saying he had worked really well over the last two or three years, and added that the bowling attack was the star of the show.
“He has come from the Air Force and used to be a volleyball player,” Mominul added. “Our coaching staff did a lot of work to support him and helped him bowl in the right areas, and it was an unbelievable spell from him.
“The bowlers played the biggest part in this win. Winning a Test match with four bowlers is unbelievable.”
Mominul was also keen to temper expectations for Test cricket’s ninth-ranked side despite the massive win.
“It helped that there was no expectation from us,” he said. “And I also want to say that don’t expect us to become number five or six in the world in Tests in the next one or two years.”
The second Test of the series will be played at the Hagley Oval in Christchurch from Jan 9-13.