The word traficaban is the imperfect form of traficar in the third person plural.
See the full traficar conjugation

traficar

Con posterioridad a la adopción de medidas por el grupo, se iniciaron investigaciones aduaneras y judiciales de diversas personas de las que se sospechaba que traficaban con diamantes.
In the wake of action taken by the task force, customs and judicial investigations were instituted against various persons suspected of trafficking in diamonds.
Lamentablemente, como lo saben las Naciones Unidas, a su costo, un gran número de efectivos en el terreno tiene poco entrenamiento; otros, en el decenio de 1990, traficaban con mujeres.
Unfortunately, as the United Nations knows, to its cost, a large number of the troops it fields are poorly trained; others, in the 1990s, trafficked in women.
Bueno, al menos no traficaban con drogas.
Well, at least they weren't doing drugs.
La Comisión de Investigación trataría de identificar a los mineros, las instituciones y los Estados que traficaban en diamantes y esperaba establecer un mecanismo eficaz de fiscalización.
The Commission of Inquiry would try to identify diamond miners, institutions and States involved in the trafficking of diamonds and hoped to put an effective control mechanism in place.
Los piratas traficaban con mujeres y esclavos.
The pirates trafficked women and slaves.
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