Virat Kohli's India has burnished their formidable home record with a 3-1 series victory over England - the tourists flunking another trial-by-spin inside three days, in the fourth and final test.
India's 13th consecutive test series victory at home also secured their place in the June final of the World Test Championship against New Zealand.
In a sign of India's strength, they won the last two matches in a total of five days - the usual duration of one test match - at Ahmedabad's Narendra Modi Stadium.
Once again, Ravichandran Ashwin and Axar Patel were the architects of their victory by an innings and 25 runs in the final match.
The spinners took all 10 wickets in England's second innings. They finished the series with a combined haul of 59 wickets, even though Patel did not play the opening test which England won.
"The first game was a bit of an aberration, just a hiccup, when England outplayed us," Kohli said.
"You're obviously happy when you're winning so many series, but there are always things to improve, like after the first game in Chennai, we had to pick up our body language."
After a below-par 205 in the first innings, England needed a vastly-improved batting performance in the second to stay alive, but their frontline batsmen let them down again.
Barring Dan Lawrence, who scored 46 and 50, the rest looked scarred from their struggles against spin in the previous match at the same venue.
Jonny Bairstow registered his third duck in four innings, which may render his place in England's test squad untenable.
Root finished as the top-scorer in the series following his 218 in the first test, but it was otherwise a miserable batting display by his side.
England crossed the 200-mark only twice in eight innings and repeatedly rejigged their combination in line with their policy to rest multi-format players.
They failed to read the third-test track, fielding a four-pronged seam attack on a spinners' paradise.
By contrast, India's spinners sowed seeds of doubt in the mind of the English batsmen, most of whom played for spin and then fell to deliveries that did not turn.
"The last three games have been testing for us and we haven't been able to match India," said Root, backing their rotation policy.
"The world we are living in now is not going to go away, it's really important we understand that and look after our players.
"It's a big year of cricket, there's three formats to consider and we can't keep playing guys until they fall over."
India exploited their home advantage to win three matches in a row.
Ashwin's all-round brilliance helped level the series in Chennai and Patel bowled them to victory inside two days in the third match in Ahmedabad.
Rishabh Pant turned the final test with a match-winning century, before the spinners completed the rout.
The white-ball leg of the series begins next week with a five-match Twenty20 series followed by three one-day internationals.