Theunis de Bruyn topscored for South Africa with a gutsy 101.
Sri Lanka on Monday completed a 2-0 Test sweep of South Africa to record their first series win over the Proteas since 2006.
Theunis de Bruyn's gutsy century went in vain as the visitors were all out for 290 in the second session of day four in Colombo.
The 199-run win, which came with more than a day to spare, was due to Sri Lanka's tireless spin trio of Herath, Akila Dananjaya and Dilruwan Perera who together claimed all 20 South African wickets.
Such was their dominance that home captain Suranga Lakmal, lone paceman in their attack, did not bowl in the first innings and sent down only two overs in the second before withdrawing himself and watching his spinners run riot against the leaden-footed South Africans.
It was South Africa's first Test whitewash since they went down in the island nation 2-0 in a two-match series almost 12 years ago.
Sri Lanka had wrapped up the first Test in Galle within three days, reducing South Africa to 73 in the second innings - their lowest Test total since readmission to international cricket.
In the second Test, Sri Lanka scored 338 in their first innings and South Africa could only respond with 124 as versatile off-spinner Akila Dananjaya made hay, taking five wickets.
The hosts then scored 275 for five before declaring halfway through the afternoon session on day three, setting the visitors a highly improbable victory target.
They were already five wickets down for 139 at stumps on Sunday, with Dananjaya dismissing du Plessis for seven and Herath getting Hashim Amla for six.
The wickets fell despite a comedy of errors from Sri Lanka, who dropped two catches, wasted both their reviews - on successive balls - and could have had Dean Elgar out twice beforehand had Perera not overstepped.
Theunis de Bruyn and Temba Bavuma kept the spinners at bay for most of the first session on Monday, putting on a valiant sixth-wicket stand of 123.
Their partnership was South Africa's best ever in a fourth innings in Asia, and was by a distance their biggest of the series, the previous best having been worth only 64.
De Bruyn was especially impressive, sweeping judiciously and defending doggedly on a tough surface, while Bavuma was also adept at picking gaps on the leg side and rotating the strike. Bavuma's resistance ended just after he was caught behind off left arm spinner Herath for 63.
He also had wicketkeeper-batsman Quinton de Kock lbw for eight on the stroke of lunch.
After lunch de Bruyn recorded his maiden century -- South Africa's only one of the series -- but was bowled by Herath for 101.
"Right through the series we didn't have that ability to score partnerships. I think we only had three partnerships of 50 and above the whole series," Faf du Plessis, South Africa's crestfallen skipper, said Monday.
"But once again you have to give credit to the opposition. They were able to put us under pressure for long periods of time and therefore we made a lot of mistakes," he said.
"In hindsight I think we definitely would have played a second spinner. Our thinking was on this surface that the ball would reverse (swing) but there was zero reverse swing this innings."
Sri Lanka, meanwhile, will take particular joy in this victory, as it came in the absence of their regular captain and middle-order batsman Dinesh Chandimal, who was suspended following a ball tampering scandal.
The home side's coach Chandika Hathurusingha was also not allowed to be in the team dressing room during match days after being sanctioned over the same incident.
(With Agencies Inputs)
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
 "SL v/s SA")
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
)
){kind=small}
){kind=small}
)
)
)
)
)
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}