His group filled a void when a few high profile cocaine trafficking groups in Amsterdam fell out.

You had the group around Gwenette Martha and the group around Samir Bouyakhrichan and Houssine Ait S. that got a lot of coverage and were consistently falling out with other groups, domestic and international.
Martha fell out with some of his former lieutenants (especially the Moroccan members of his organization), no longer had the respect of the Surinamese and Antillean gang members and Moluccan bikers (Martha for the longest time favored working with Moroccan guys as opposed to the guys he grew up with in South Amsterdam) and on top of that he was regarded as untrustworthy by his main suppliers (the Dawes crime family from Nottingham) when things went wrong with a few shipments and the Nottingham guys brought heat on them in the Netherlands because Martha didn't set things right himself. He also lost the backing of the major old school Amsterdam penoze guys like Danny K. In short, Martha's organization was in shambles.
Bouyakhrichan also started getting into wars with other groups, most notably a group of Brabant Travellers from Breda around John G. Bouyakhrichan did a lot of business with the Irish right when the Irish groups in Dublin were warring with each other; which also made him a mark.

Taghi's group was one of the groups that were getting stronger in silence when the high profile groups were getting into constant battles. Taghi also had a solid network; he had a group of close youth friends from different backgrounds that also brought him into connection with other groups, he solidified his bond with the family of Said R. (which is a large clan with strong criminal connections all the way in Morocco) and formed a partnership with Rico, who had a lot of contacts himself. Rico always had strong connections with Ajax hooligan groups and in turn also with old school Dutch Penoze guys.

In short, Taghi's group got this strong, because they had a stable and large network in a time when the organizations of high profile cocaine traffickers were in shambles.