What are people arguig about?
A lot of people from Bajaur and Swat have settled in Karachi. Karachi has the largest concentration of pashtuns in any one area.
Bajauris have settled in most towns and cities all over pakistan doing jobs such as selling footwear, cobblers, shoe polishers, selling clothes, - they have extensive networks which support one another probably moreso than other Pashtuns.
Karachi has a large population of Swatis. I dont think Swatis have settled in any other areas as much as they have done in Swat.
Pashtun migration is complex. For example Wazris are more likely to go to Karachi for work rather than any other city such as lahore which is much nearer.
Karachi is represented very well by most pashtun areas and tribes