date?
edithttps://ast.wikipedia.org/wiki/Henry_Kissinger dates the picture to July 1971. ("Pequín en xunetu de 1971" = July according to: https://ast.wikipedia.org/wiki/Xunetu )
https://en.wikipedia.org/wiki/1971_in_China does not date – and shows no event for this month.
Zhou Enlai (in the picture) died after illness Jan 1976.
See: https://en.wikipedia.org/wiki/Zhou_Enlai#Death_and_reactions
Saying further: His last major public appearance ... on 13 January 1975. / Surgical operation to be performed in June 1974 ... / Bleeding 1974 ... / diagnosed with bladder cancer in November 1972 (but he had not been told, ordered by Mao)
This makes negotiations with Mao and Kissinger later than 1972/1974/Jan 1975 less and less probable.
https://en.wikipedia.org/wiki/1971_in_China tells about a secret visit of Kissinger in Bejing in Nov 1971. Is that possibly the occasion of the picture?