China + 1 Has a Map, and It Runs Through Southeast Asia

The verticals with the highest structural concentration risk are the ones moving fastest into Thailand, Vietnam, and Malaysia. This is the field guide to which category goes where, and why a second source is no longer optional.

"China + 1" is usually said as a slogan. Underneath it is a precise, vertical-by-vertical map of where global manufacturing is dangerously concentrated and where the second source is actually being built. The pattern is consistent: the categories carrying the highest single-jurisdiction concentration are the same categories whose diversification anchors are landing hardest in the Southeast Asia corridor, Thailand, Vietnam, and Malaysia. This is the definitive read on which verticals are moving, where they are going, and what it changes for any buyer building a real second source.

Start with the risk, because the risk is what makes the move rational. Across the verticals MPBxChange tracks, global capacity is not spread evenly, it is piled into one country per category. Semiconductors: Taiwan holds 68.8% of global foundry capacity, anchored by TSMC dominance. EV battery cells: two Chinese makers, CATL at 39.2% and BYD at 16.4%, together control 55.6% of global supply. Solar modules: China holds roughly 80% of global manufacturing capacity. Regional HVAC clusters around a handful of Japanese-led names at roughly 60%. These are not forecasts. They are the structural baselines our contract-review engine uses to flag single-jurisdiction exposure the moment a buyer sources from the concentrated country.

The concentration map, by vertical

Each figure below is the share of global (or regional) capacity held by the single most-concentrated jurisdiction in that category. The higher the number, the more a single tariff action, sanction, export control, or force-majeure event takes the whole category offline at once, which is precisely why these are the verticals under the most diversification pressure.

Where each vertical is actually moving

The corridor is not a single destination, it is a set of category-specific anchors. The same diversification logic our detectors recommend at contract-review time names a different landing zone per vertical: for semiconductors, assembly-test-and-packaging (ATP) in Thailand or final assembly in Malaysia; for EV batteries, Thailand (Sunwoda) or Vietnam; for solar, Thailand (Trina) or Vietnam. These are the natural second-source anchors precisely because they sit outside the concentrated jurisdiction while staying inside the same logistics corridor.

• Semiconductors (TW 68.8% foundry) → second source via ATP / packaging in Thailand or back-end assembly in Malaysia.
• EV batteries (CN 55.6% of cells) → Thailand (Sunwoda) or Vietnam for cell and pack diversification.
• Solar modules (CN ~80%) → Thailand (Trina) or Vietnam, the two anchors already absorbing module capacity out of China.
• Automotive components → the corridor already carries a 42% Thailand-corridor share among suppliers we can place by country, with Japan and the US as the next-largest origins.
• Data center equipment → the least corridor-concentrated today (10% Thailand-corridor share), still skewed US / EU, meaning each onboarded corridor supplier is a genuinely new second source rather than a re-shuffle.

The corridor is already real in the supplier base

Diversification anchors are not aspirational. Looking at suppliers we can place by country across the verticals MPBxChange has ingested, the Thailand-corridor share is already material, and it is highest in exactly the categories under the most concentration pressure. EV batteries lead at 57%, with China, Korea, and the US as the top supplier origins. Semiconductors sit at 43% (US, Japan, Germany leading). Automotive is at 42% (US, Japan, Germany). Solar trails at 28% (US, China, Germany), and data center at 10% (US, Germany, France). The verticals with the scariest concentration numbers are the ones whose corridor footprint is filling in fastest.

“The verticals carrying the highest single-jurisdiction concentration are the same ones whose second source is landing hardest in the corridor. Concentration risk and corridor opportunity are the same map, read from opposite ends.”

Why a second source stopped being optional

When a category is 68.8% or 80% concentrated in one jurisdiction, sourcing from that jurisdiction is not a procurement choice, it is alignment with the global concentration. A single tariff, sanction, force-majeure, or natural-disaster event then hits the entire category at once, not just one supplier. That is the structural risk a designated-backup-supplier clause exists to neutralize: it names an alternate-jurisdiction source before the disruption, not after. The same logic compounds at the buyer level. Once a buyer's own supplier pool crosses 60% in one country, single-country pools carry a median dispute-resolution cycle of 14 months when that country imposes export controls or undergoes political disruption, long enough to miss an entire product cycle.

There is a tariff dimension on top of the resilience one. For Western buyers sourcing China-origin goods in tariff-exposed categories, PCB, semiconductors, solar, EV batteries, and automotive all fall under US Section 301 exposure, and CBAM adds an EU carbon adjustment on steel, aluminum, and related codes, re-sourcing into the corridor has carried a measurable arbitrage. Across the MPBxChange corridor dataset, buyers in that exact China-origin, tariff-exposed pattern have saved on the order of 10-18% of contract value by adding a Thailand or Vietnam alternate-source clause, with Thailand at the top of the range and Vietnam and Malaysia behind it. The second source pays for itself before the first disruption even arrives.

The convergence dividend

One under-appreciated feature of the corridor is that the same suppliers keep showing up across adjacent verticals. Twenty-one suppliers serve both automotive and solar; twelve serve both automotive and PCB; eight bridge PCB and semiconductors. A buyer who qualifies a corridor supplier in one category often finds that same name already validated for the adjacent one, which means the cost of building a second source falls every time you build the next one. Diversification in the corridor is not a series of isolated qualification projects; it is a compounding directory where trust earned in one vertical carries into the next.

What it means for procurement

• Treat the concentration numbers as a trigger, not trivia: if your category is the 68.8% (semi-TW), 55.6% (EV-CN), or ~80% (solar-CN) case, a designated-backup-supplier clause naming an alternate jurisdiction belongs in the contract now.
• Match the anchor to the vertical: semi → ATP/packaging in TH or assembly in MY; EV batteries → TH (Sunwoda) or VN; solar → TH (Trina) or VN. The corridor is category-specific, not generic.
• Watch your own pool, not just the world: once any single country crosses 60% of your prior contracts, award the next one or two to a non-concentrated alternate to pull exposure back under the line.
• Price the tariff arbitrage in: for China-origin goods under Section 301 or CBAM exposure, a TH/VN alternate-source clause has historically recovered 10-18% of contract value, quantify it before you renew.
• Exploit convergence: a corridor supplier already qualified in an adjacent vertical (auto↔solar, auto↔PCB, PCB↔semi) is a faster, cheaper second source than a cold qualification.
• Remember the frontier: solar (28%) and data center (10%) corridor shares are still thin, so early second-source positions there face less competition than the already-crowded EV and semi corridors.