Supplementary Information: Table 1 Radiocarbon dates carried out at sites on the Tibetan Plateau discussed in the text.

Site Name / Stratigraphic Information / Phase / Lab. No. / Date (C14 years) / + - / Plant Part
Karuo / F18-170cm / Early / ZK0816 / 5120 / 300 / Wood charcoal
Karuo / T62(3)F17:84 / Early / ZK0815 / 4810 / 100 / Wood charcoal
Karuo / T102(3) F18 / Early / BK79072 / 4550 / 100 / Wood charcoal
Karuo / T41F9(3)西壁 / Early / BK79069 / 4540 / 80 / Wood charcoal
Karuo / T102(3) F19 / Early / BK79071 / 4490 / 90 / Wood charcoal
Karuo / T62(3)F17 / Early / WB79-58 / 4460 / 85 / Wood charcoal
Karuo / F7:24陶罐下 / Early / ZK0810 / 4420 / 110 / Wood charcoal
Karuo / T1(2)-30cm / Late / ZK0617 / 4390 / 100 / Wood charcoal
Karuo / T103(4)F31 / Early / BK79073 / 4380 / 100 / Wood charcoal
Karuo / T102(3)F19 / Early / ZK0817 / 4300 / 90 / Wood charcoal
Karuo / (3)F29西北角柱洞 / Early / BK79077 / 4280 / 80 / Wood charcoal
Karuo / T61(3)F14烧土下 / Early / ZK0813 / 4280 / 100 / Wood charcoal
Karuo / F3(3) / Early / ZK0637 / 4190 / 90 / Wood charcoal
Karuo / F3(3) / Early / BK78044 / 4180 / 120 / Wood charcoal
Karuo / T42(4)F8 低 / Early / BK79074 / 4160 / 80 / Wood charcoal
Karuo / T4(3) F9 / Early / ZK0812 / 4160 / 100 / Wood charcoal
Karuo / T56(3) F20 柱洞 / Early / WB79-51 / 4120 / 140 / Wood charcoal
Karuo / 02XCK T7 H2 / Late / BA111228 / 4115 / 25 / Foxtail Millet
Karuo / T4,T14F12(2)(3) / Early / BK79070 / 4110 / 100 / Wood charcoal
Karuo / T22(2)-133 cm / Early / ZK0620 / 4110 / 80 / Wood charcoal
Karuo / T42(4)F8 东壁 / Early / ZK0811 / 4060 / 100 / Wood charcoal
Karuo / T102(3)F19 柱洞 / Early / WB79-52 / 4030 / 75 / Wood charcoal
Karuo / F15柱洞内 / Early / ZK0814 / 4030 / 100 / Wood charcoal
Karuo / F4(6) / Early / BK78046 / 4000 / 85 / Wood charcoal
Karuo / 02XCK T7 H1 / Late / BA111229 / 3995 / 25 / Foxtail Millet
Karuo / 02XCKT7东壁3下H4 / Late / Beta325960 / 3980 / 40 / Broomcorn Millet
Karuo / T24,T13, T23F5 / Late / ZK0636 / 3980 / 90 / Wood charcoal
Karuo / 02XCK T7 H1 / Late / BA111230 / 3965 / 25 / Undet Fragments
Karuo / T12(2) / Late / ZK0619 / 3950 / 95 / Wood charcoal
Karuo / 02XCKT7东壁3下H4 / Late / BA111227 / 3945 / 20 / Undet Fragments
Karuo / F5(4) / Late / BK78045 / 3940 / 80 / Wood charcoal
Karuo / 02XCKT7东壁3下H4 / Late / BA111226 / 3910 / 25 / Foxtail Millet
Karuo / T62(3)F17 / Late / BK79068 / 3910 / 90 / Wood charcoal
Karuo / F4 柱内 / Late / WB78-34 / 3910 / 130 / Wood charcoal
Karuo / 02XCKT7 F1 / Late / BA111231 / 3895 / 25 / Undet Seed
Karuo / T102(3) / Late / WB79-54 / 3870 / 70 / Wood charcoal
Karuo / T103(4)F31 / Late / ZK0820 / 3870 / 100 / Wood charcoal
Karuo / F5 / Late / WB78-35 / 3840 / 80 / Wood charcoal
Karuo / F1 / Late / WB78-37 / 3820 / 90 / Wood charcoal
Karuo / F30(2) / Late / ZK0819 / 3820 / 80 / Wood charcoal
Karuo / F22(2) / Early / ZK0818 / 3790 / 80 / Wood charcoal
Karuo / F22-29 / Early / WB80-63 / 3760 / 95 / Wood charcoal
Karuo / T13(2)-150 cm / Late / ZK0618 / 3760 / 170 / Wood charcoal
Karuo / T42(4)F8 低 / Early / WB79-57 / 3740 / 70 / Wood charcoal
Karuo / T59(2)F10 / Early / WB79-59 / 3610 / 165 / Wood charcoal
Karuo / F3 / Early / WB78-36 / 3600 / 95 / Wood charcoal
Karuo / T4(3)F9东北角木柱 / Early / WB79-55 / 3580 / 95 / Wood charcoal
Karuo / T4,T14F12(2)(3) / Late / WB79-53 / 3540 / 105 / Wood charcoal
Karuo / 02XCKT7K1 / Late / BK200264 / 4105 / 70 / Wood charcoal
Karuo / 02XCKT7F1 / Late / BK200265 / 4070 / 70 / Wood charcoal
Karuo / 02XCKT3F1 / Late / BK200266 / 3890 / 70 / Wood charcoal
Karuo / 02XCKT7H2 / Late / BK200267 / 3975 / 70 / Wood charcoal
Karuo / 02XCKT7H1 / Late / BK200268 / 3848 / 70 / Wood charcoal
Karuo / 02XCKT1 (4) / Late / BK200269 / 4716 / 80 / Wood charcoal
Changguogou / H2 / 2958 / 102 / Wood charcoal
Changguogou / H2 / 2814 / 99 / Animal Bone
KyungLungSilverCastle / KLB区北端 / BA111234 / 1780 / 20 / Carbonized Matrix
KyungLungSilverCastle / KLB区北端 / BA111235 / 1745 / 20 / Hordeum grain
KyungLungSilverCastle / KLB区北端 / BA111236 / 1740 / 20 / Twig
KyungLungSilverCastle / Structure 66 / BA111237 / 1260 / 20 / Dung
KyungLungSilverCastle / Structure 66 / BA111238 / 1190 / 20 / Hordeum sp.
KyungLungSilverCastle / KL04-32 / ? / ? / Wood charcoal
KyungLungSilverCastle / KL04-66 / ? / ? / Wood charcoal
KyungLungSilverCastle / 04KLB / ? / 1910 / 104 / Wood charcoal
KyungLungSilverCastle / 04KLA S66.2 / ? / 2110 / 115 / Wood charcoal
KyungLungSilverCastle / 04 KLA S66.3 / ? / 1810 / 109 / Animal bone
KyungLungSilverCastle / 04KLA W1 / ? / 3230 / 160 / Sediment
KyungLungSilverCastle / 04KLA W2 / ? / 3550 / 740 / Animal bone
KyungLungSilverCastle / 04 KLB N1 / ? / 2460 / 100 / Sediment
KyungLungSilverCastle / 04 KLB N2 / ? / 2890 / 153 / Sediment
KyungLungSilverCastle / 04 KLA S10.1 / ? / 3280 / 143 / Wood charcoal
KyungLungSilverCastle / 04 KLA S32.1 / ? / 3470 / 958 / Sediment

Supplementary Information 1

Radiocarbon dating at the site of Karuo

According to the original excavation report, two phases of occupationwere present at Karuo. During the first season of excavation, a totalof 42 radiocarbon dates were carried out on wood charcoal. Despite theproblems inherent with dating wood charcoal, it is apparent, that thefeatures dating to early occupation of the site largely pre-date 2500cal. BC, with the earliest dates reaching approximately 3500 cal. BC.Samples dating to later occupation of the site appear to post-date2700 cal. BC. The fact that these dates were carried out on woodcharcoal may mean that the start of occupation at the site wasconsiderably later. There are several reasons for this: 1.) thecharcoal may contain clay which contained old carbon, 2.)charcoal mayhave been derived from the inner rings of trees leading to an earlierdate, or 3.)or that wood resources were reused by the inhabitants ofthe site. This is not entirely unexpected for a site on the Plateauwhere wood is a limited resource,4.) Perturbation could have led tothe movement of earlier material into later occupations. We carriedout an additional 7 dates on seeds found in contexts dating to thelater phase and these overlapped neatly with dates carried out on woodcharcoal and appeared if anything to date to the earlier part of thisphase

SI Figure 1: Calibrated Radiocarbon Dates for the three phases represented at Karuo showing the two-sigma probability intercepts with the calibration curve (from IntCal 2009). Dates are in order of uncalibrated radiocarbon determination (see Table S1 for uncalibrated dates).

Supplementary Information 2: Kyung-Lung Radiocarbon dating

Following the small scale excavations at the Kyung-Lung Mesa, eleven samples were submitted for radiocarbon dating including wood charcoal and bulk soil samples. Two radiocarbon dates were run on wood charcoal and animal bone from Structure 66, which, respectively, date the structure to roughly 396 BC – 120 cal. AD) and 45 cal. BC – 528 cal AD.Previously, two radiocarbon dates carried out on sediment taken in area B yielded dates of 753 – 417 cal BC and 1291 – 906 cal BC. After analyzing macrobotanical remains from these two units, we submitted a total of five pieces of dung or grain caryopsis for direct dating. Those from Structure 66 yielded a range of 694 – 880 cal. AD, which is substantially later than previous dates carried out on wood charcoal and sediment. It is highly likely that this is because wooden beams and were re-used at the site long after the tree had been cut down. Four direct AMS dates on specimens from the northern of area of the site yielded a range of 220 – 334 cal AD, again much later than previously estimated by the excavators.