It was the Philistine wars which first created the Judah of later days.
They forced Hebrews, Edomites, and Kenites to unite against the common enemy, and welded them into a single whole.

Though the three peoples still continued to be spoken of separately, this was but a survival of ancient modes of speech, and after the accession of David all distinction between them disappears.

From this time forward the kingdom of Judah is one undivided community.
But the Amalekites were ever on its borders.

The Amalekite of the Old Testament is the Bedawi of to-day.

Now, as ever, he is the scourge of his more settled neighbours, whose fields he harries and whose families he murders.