After signing for United, Sanchez revealed he's dreamed of joining the club since he was a "young boy".
Sanchez scored 60 goals in 122 Premier League appearances for the Gunners, who he joined from Barcelona in 2014.
While Van Persie departed a year before his contract expired after, like 29-year-old Sanchez, rejecting a new deal, the Chilean has followed the same road for a knockdown price six months before he could walk out of the club for nothing.
Mkhitaryan spoke to Arsenal's website after signing his contract; "I'm very happy that we could finish this deal and I'm very happy to be here". "It's a dream come true because I've always dreamed of playing for Arsenal".
The 29-year-old forward opted to move to Jose Mourinho's Red Devils, where he will earn a wage upwards of £350,000 per week plus bonuses, after a long-touted move to Manchester City fell through.
"He will bring his ambition, drive and personality, qualities that make a Manchester United player and a player that makes the team stronger and the supporters proud of their club dimension and prestige".
"He's a very professional player who has been committed until the last minute", the Frenchman told Arsenal Player.
The Armenian global joined the Reds from Bundesliga outfit Borussia Dortmund in July 2016, making his competitive debut as a substitute in United's 2-1 victory over Leicester City in the Community Shield at Wembley the following month. "All we achieved and the good moments that I gave to the club, I want to dedicate it to the fans, they are the most important".
He spent two lengthy periods out of favour under Mourinho but did play a huge part in United's Europa League triumph in 2016-17, scoring the second goal in the 2-0 victory over Ajax in last May's final.
"There are people (former club players) who have spoken with no knowledge of what happens inside the club and cause damage".