"The novelty has worn off" is an odd phrase, with unnecessarily limited, negative connotations. Sometimes the novelty fades and the excitement remains. Afghanistan are by far the most interesting team at the World Twenty20 which started in Sri Lanka on Tuesday; it's just that they are no longer new. They are now part of international cricket's furniture. It is not a shock they qualified. It would have been a surprise had they not done so.

Afghanistan – who play India in Group A on Wednesday before facing England on Friday – are a team of irrepressible optimists; full of character, charm and innocence; free of the cynicism and entitlement that pollute modern sport. They are subject to the unique goodwill, affection and gratitude that only occurs when you are exploring virgin territory on behalf of your country. Theirs is a tale the whole cricket world has embraced. The more you delve into their story, the more you fall in love with it. If you have not yet seen the life-affirming documentary Out of the Ashes, your LoveFilm list is in urgent need of revision.

"There is a lot of problems in the world today, you know?" the then national coach Taj Malik says in the documentary. "And everywhere, everywhere, there is complex fighting. The solution of all the problems ... is cricket." Nawroz Mangal, the captain, estimates the cricket-playing population of Afghanistan at more than 500,000. "After participating in this World Cup, if we do better, I expect 30 to 40% of the population to start playing cricket." The swashbuckling wicketkeeper-batsman Mohammad Shahzad says their participation "could be a positive step towards bringing peace to the country".

The word "journey" has become a little hackneyed in the reality TV age, but Afghanistan's journey is worth revisiting. It began in refugee camps during the Soviet occupation of 1979-89, where cricket was played using shoes for stumps and balls made out of torn-up shirts. The national team became affiliated to the ICC in 2001, when they went on their first tour, a trip across the Pakistan border from Kabul to Rawalpindi. As recently as 2008 they were playing in Division Five of the ICC World Cricket League against Japan, Jersey, Singapore, Botswana and the Bahamas. That was the start of a series of qualifiers for the last 50-over World Cup which took them to Jersey, Tanzania, Argentina and finally South Africa. Their dream of World Cup qualification ended with defeat to Canada in 2009 but they received ODI status at the end of the same tournament.

Afghanistan then qualified for the World T20 in 2010, where they were beaten by India and South Africa. Last month they played their first ODI against Australia and were far from embarrassed during a 66-run defeat. Mohammad Nabi clubbed four sixes while the boyish No9, Gulbodin Naib – whose endearing fixation with his Popeye muscles was a recurring theme of Out of the Ashes – showed the value of that gym work by hammering three sixes in nine balls off Mitchell Johnson and James Pattinson.

That match is one of only two ODIs against a Test-playing nation – they also lost to Pakistan by seven wickets in February – but they have an overall record of 12 wins and 11 defeats in that form of the game. In T20 internationals their record is won six and lost five, again with defeats in both their matches against a major nation. They have not played enough games to qualify for a place in the ICC T20 rankings, although their points total would put them 10th, above Ireland and Zimbabwe – and, for a few days a fortnight ago, Australia.

Afghanistan are probably not yet ready to beat one of the big nations. That day will come, however, and a victory against England – who have lost to Associate nations in two of the past three global tournaments – should not be completely discounted. "We have a very competitive team," says the ACB chief executive Hamid Shinwari, "and I hope that they will put up a better show in this year's event."

They were comfortably beaten in both matches in the Caribbean two years ago, although they left their mark. The lower order swung merrily to recover from 14 for six and 32 for eight to reach 80 against South Africa, while Hamid Hassan took three for 21 in that match and one for eight from three overs against India.

Hassan is the best fast bowler among the Associate and Affiliate nations. Afghanistan are not yet Associate members of the ICC, and share Affiliate status with, among others, Cameroon, Luxembourg and the Isle of Man. His former coach, the Pakistan wicketkeeper Rashid Latif, says he is "good enough to represent even a full nation in a developed team". His strength, yorkers and ability to swing the ball both ways, prompted Clive Lloyd to say that he reminded him a little of Waqar Younis. As a child he played in secret, because his father hated cricket. Now he loves expressing his talent in public. Hassan's aggression and love of wearing bandanas – with a lick of sunblock on his cheek – have led to him being described as the "Rambo of Afghanistan cricket".

He has been included in the squad despite fitness concerns. Hassan was badly injured playing for an Associate and Affiliate XI against England in Dubai in January, when he dismissed Andrew Strauss and Jonathan Trott during a lively spell, and has bowled only a handful of overs in the past eight months. In his absence, Dawlat Zadran has been Afghanistan's premier new-ball bowler: he was the only non-Irishman included on the five-man shortlist for Associate and Affiliate Player of the Year at last week's ICC Awards.

Fast bowling is probably Afghanistan's strongest suit, but batting is their most eye-catching. They are not especially savvy and do not really do nurdling, instead preferring to embrace an unashamed six-addiction. Nabi clouted five in a 22-ball half-century during a warmup against Sri Lanka A on Saturday. Overall Afghanistan hit 13 sixes in their 20 overs.

It has almost become a cliche to refer to Afghanistan's cricketers as fearless, yet that is the way they play the game. Nobody exemplifies that more than the hard-hitting opener, Karim Sadiq, who goes after bowlers from the moment the umpire calls "play". In the final of the World T20 qualifiers against Ireland, he pulled the first ball of the match from Warwickshire's Boyd Rankin over the ropes.

When Afghanistan met Pakistan in February, Shahzad reverse swept Saeed Ajmal, the world's best spinner, for an amazing six. And in a warmup game ahead of the last World T20, Sadiq smashed consecutive short balls from Shoaib Akhtar to the boundary, one of them on to a roof. As Shoaib prepared to share a few four-letter insights, Sadiq got in with the pre-emptive sledge: "This is not club cricket." It was international cricket, and it is where Afghanistan unquestionably belong.• This is an extract from the Spin, the Guardian's free weekly cricket email. To sign up, click here.