Samson did not rule over all 12 of the tribes, but seemingly only over the Hebrews in his area. The people probably accorded him the sort of vague prerogatives they were willing to give to a military hero.
In the days.
This seems to mean in the 40-year period of Philistine oppression (see p. 128).
Twenty years.
Evidently this 20-year period of Samson’s leadership of the southern Hebrews was near the end of the 40 years of Philistine oppression, for Samson was born in the early years of the oppression (PP 560). The fact that the Hebrews did not join Samson in the revolt against the Philistines but remained subservient to them suggests that his rule may have been confined strictly to his own small locality. (see ch. 16:31).