Jazakallahkhaira, btw is 'Muhammadiyah' frowned upon by the majority of Muslims in Indonesia? Is he's followers called 'Muhammadiyahs'?
Muhammadiyah is a Reformist organization, but majority of Indonesian Muslims are Traditionalist. Muhammadiyah is the second biggest in "the big three Muslim organization in Indonesia".
The Traditionalist are Muslims who perform 'traditions' like read tahlil for deceased person, read surah Yaseen in congregation, and other traditions like these. Reformist are Muslims who "bring Islam back to original form" with eliminate traditions which not based on sunnah. However, Reformists are not (and different than) Salafis.
Muhammadiyah is the first organization that established among those big three (1912, in Yogyakarta). They declare themselves as "free from any madhab". Their mision is eliminate "TBC"
(tachyul, bid'ah, churafat)
The second organization is "Persatuan Islam / Persis" (unity of Islam) which established in Bandung in 1923 by a Muslim reformist group that lead by Haji Zamzam and haji Muhammad Yunus. As Reformist, Persis is stricter than Muhammadiyah in eliminate bid'ah. Persis is organization that 'introduced' placing hand on chest when salah.
Existency of Muhammadiyah and Persis got resistance from the Traditionalist who tried to maintain their traditions. So, lead by KH Hasyim Asy'ari, the Traditionalist established their organization "Nahdlatul Ulama (NU)" in 1926.
Now NU is the biggest Muslim organization in Indonesia. Muhamaddiyah the second, Persis the third.
Muhammadiyah mission is more than just eliminate
(tachyul, bid'ah, churafat), but also to build "modern developed Islamic society". So, they established many universities, schools, and hospitals.
http://id.wikipedia.org/wiki/Daftar_perguruan_tinggi_Muhammadiyah
(list of universities and colleges that owned by Muhammadiyah. Not included schools in level elementary, secondary and high school)
Universitas Muhammadiyah in Malang.
Oh and did he moved to Tanah Malaya before he passed away?
Who? Kyai Haji Ahmad Dahlan? or Buya HAMKA?. No, they did not move to Tanah Malaya.
As-Syeikh Tahir Jalaluddin moved to Tanah Malaya. But I think he's not in Muhammadiyah.