After a long hiatus following the collapse of the palatial civilizations of the Bronze Age, wall and panel painting was reintroduced to Greece during the Early Iron Age. The first archaeological finds date from the advanced 7th century bce and include mural fragments and clay plaques used to decorate temples. Early examples (down to the early 5th century bce) are polychrome, with strong outlines and flatly painted surfaces without any sense of volume or depth of field. Their themes are often taken from myth, contemporary warfare, and religious rituals; inscriptions are customarily used to name the figures or scenes depicted.A series of breakthroughs occurred in the 5th century bce. Composition became more sophisticated, an innovation attributed to Polygnotus of Thasos; shading and tonal contouring were introduced toward the end of the century, allegedly invented by Apollodorus of Athens. Painters often acquired high social status, as we may infer from stories about Zeuxis of Heraclea or Parrhasius of Ephesus. According to later authorities, the 4th century bce saw the greatest achievements of Greek painting and some works from this era, mostly from burial monuments, survive.