Does anyone know what Season 6 will be based on since Winds of Winter hasn't come out yet?

''In contrast to the vorige seasons, it will largely rely on original content not found in George R. R. Martin's A Song of Ice and brand series, but will also adapt material from the upcoming sixth novel in the series, The Winds of Winter, as well as some content from the fourth and fifth novels, A Feast for Crows and A Dance with Dragons.''