Conversation so far:
Did the band reunite during this time frame?
In 1990, the former line-up of van Leer, Akkerman, van der Linden, and Ruiter reunited for the first time since 1975.
Did anything particular happen during the reunion?
The four played a 40-minute set at the Americahal in Apeldoorn on 20 April that was broadcast as part of the Oud van Goud television special.
Was there anything else important happening?
On 17 May the group, minus Akkerman, mimed a performance of "House of the King" on the Service Salon television program on AVRO-TV.
What were some of their songs?
Hocus Pocus.
Are there any other songs?
In the 63 days they spent recording from April to May 1984, around 30 tracks were completed with several additional musicians.
Did they do any tours during this time frame?
Focus was released in March 1985 by Vertigo Records which reached number 33 in the Netherlands.
The pair followed the album with promotional videos and a local four-date tour.
Are there any other highlights during their reunion?
In 1999, van Leer attempted to reform Focus with Cleuver, Ruiter, and Dutch guitarist Menno Gootjes.
They performed several live dates in the Netherlands.
Did  their band only play in other countries during this time?
CANNOTANSWER.

Question: Did anything happen that ended their reunion in 1999?
Self-contained rewrite: Did anything happen that ended Focus' reunion in 1999?